21403444644 has 48 divisors (see below), whose sum is σ = 55590192000. Its totient is φ = 7121652768.

The previous prime is 21403444637. The next prime is 21403444663. The reversal of 21403444644 is 44644430412.

21403444644 is a `hidden beast` number, since 2 + 1 + 4 + 0 + 3 + 4 + 4 + 4 + 644 = 666.

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 = 21403444599 and 21403444608.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 117744 + ... + 238055.

It is an arithmetic number, because the mean of its divisors is an integer number (1158129000).

Almost surely, 2^21403444644 is an apocalyptic number.

It is an amenable number.

21403444644 is an abundant number, since it is smaller than the sum of its proper divisors (34186747356).

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

21403444644 is a wasteful number, since it uses less digits than its factorization.

21403444644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 356369 (or 356361 counting only the distinct ones).

The product of its (nonzero) digits is 147456, while the sum is 36.

The spelling of 21403444644 in words is "twenty-one billion, four hundred three million, four hundred forty-four thousand, six hundred forty-four".