21557302004 has 12 divisors (see below), whose sum is σ = 43114604064. Its totient is φ = 9238843704.

The previous prime is 21557302003. The next prime is 21557302027. The reversal of 21557302004 is 40020375512.

It is a happy number.

21557302004 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21557302001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 384951794 + ... + 384951849.

It is an arithmetic number, because the mean of its divisors is an integer number (3592883672).

Almost surely, 2^21557302004 is an apocalyptic number.

It is an amenable number.

21557302004 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21557302004 is a wasteful number, since it uses less digits than its factorization.

21557302004 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 769903654 (or 769903652 counting only the distinct ones).

The product of its (nonzero) digits is 8400, while the sum is 29.

Adding to 21557302004 its reverse (40020375512), we get a palindrome (61577677516).

The spelling of 21557302004 in words is "twenty-one billion, five hundred fifty-seven million, three hundred two thousand, four".