21191900544 has 96 divisors (see below), whose sum is σ = 61181560440. Its totient is φ = 7040839680.

The previous prime is 21191900537. The next prime is 21191900551. The reversal of 21191900544 is 44500919112.

It is a happy number.

21191900544 is a `hidden beast` number, since 21 + 1 + 9 + 1 + 90 + 0 + 544 = 666.

It is an interprime number because it is at equal distance from previous prime (21191900537) and next prime (21191900551).

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21191900499 and 21191900508.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 323704 + ... + 383624.

Almost surely, 2^21191900544 is an apocalyptic number.

21191900544 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21191900544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30590780220).

21191900544 is an abundant number, since it is smaller than the sum of its proper divisors (39989659896).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21191900544 is a wasteful number, since it uses less digits than its factorization.

21191900544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60248 (or 60233 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The spelling of 21191900544 in words is "twenty-one billion, one hundred ninety-one million, nine hundred thousand, five hundred forty-four".