21901778544 has 40 divisors (see below), whose sum is σ = 56614871952. Its totient is φ = 7296040960.

The previous prime is 21901778531. The next prime is 21901778687. The reversal of 21901778544 is 44587710912.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a junction number, because it is equal to n+sod(n) for n = 21901778493 and 21901778502.

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 7 ways as a sum of consecutive naturals, for example, 64017 + ... + 218864.

Almost surely, 2^21901778544 is an apocalyptic number.

21901778544 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21901778544 is an abundant number, since it is smaller than the sum of its proper divisors (34713093408).

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

21901778544 is a wasteful number, since it uses less digits than its factorization.

21901778544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 284505 (or 284499 counting only the distinct ones).

The product of its (nonzero) digits is 564480, while the sum is 48.

The spelling of 21901778544 in words is "twenty-one billion, nine hundred one million, seven hundred seventy-eight thousand, five hundred forty-four".