21644113400 has 144 divisors (see below), whose sum is σ = 63041824440. Its totient is φ = 6849964800.

The previous prime is 21644113399. The next prime is 21644113429. The reversal of 21644113400 is 431144612.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a self number, because there is not a number n which added to its sum of digits gives 21644113400.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 42455 + ... + 212345.

Almost surely, 2^21644113400 is an apocalyptic number.

21644113400 is a gapful number since it is divisible by the number (20) 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 21644113400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31520912220).

21644113400 is an abundant number, since it is smaller than the sum of its proper divisors (41397711040).

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

21644113400 is a wasteful number, since it uses less digits than its factorization.

21644113400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169934 (or 169918 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 26.

The spelling of 21644113400 in words is "twenty-one billion, six hundred forty-four million, one hundred thirteen thousand, four hundred".