21555004404 has 48 divisors (see below), whose sum is σ = 52958689280. Its totient is φ = 6804712800.

The previous prime is 21555004399. The next prime is 21555004447. The reversal of 21555004404 is 40440055512.

It is a congruent number.

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, 817629 + ... + 843579.

Almost surely, 2^21555004404 is an apocalyptic number.

It is an amenable number.

21555004404 is an abundant number, since it is smaller than the sum of its proper divisors (31403684876).

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

21555004404 is a wasteful number, since it uses less digits than its factorization.

21555004404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29620 (or 29618 counting only the distinct ones).

The product of its (nonzero) digits is 16000, while the sum is 30.

Adding to 21555004404 its reverse (40440055512), we get a palindrome (61995059916).

The spelling of 21555004404 in words is "twenty-one billion, five hundred fifty-five million, four thousand, four hundred four".