21555573402 has 32 divisors (see below), whose sum is σ = 49796835264. Its totient is φ = 6147756800.

The previous prime is 21555573401. The next prime is 21555573409. The reversal of 21555573402 is 20437555512.

It is not an unprimeable number, because it can be changed into a prime (21555573401) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9604749 + ... + 9606992.

It is an arithmetic number, because the mean of its divisors is an integer number (1556151102).

Almost surely, 2^21555573402 is an apocalyptic number.

21555573402 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21555573402 is an abundant number, since it is smaller than the sum of its proper divisors (28241261862).

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

21555573402 is a wasteful number, since it uses less digits than its factorization.

21555573402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19211774.

The product of its (nonzero) digits is 210000, while the sum is 39.

The spelling of 21555573402 in words is "twenty-one billion, five hundred fifty-five million, five hundred seventy-three thousand, four hundred two".