21555251042 has 32 divisors (see below), whose sum is σ = 35723842560. Its totient is φ = 9693331200.

The previous prime is 21555251017. The next prime is 21555251089. The reversal of 21555251042 is 24015255512.

It is a happy 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, 111167 + ... + 235517.

It is an arithmetic number, because the mean of its divisors is an integer number (1116370080).

Almost surely, 2^21555251042 is an apocalyptic number.

21555251042 is a deficient number, since it is larger than the sum of its proper divisors (14168591518).

21555251042 is a wasteful number, since it uses less digits than its factorization.

21555251042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124538.

The product of its (nonzero) digits is 20000, while the sum is 32.

The spelling of 21555251042 in words is "twenty-one billion, five hundred fifty-five million, two hundred fifty-one thousand, forty-two".