21545639090 has 64 divisors (see below), whose sum is σ = 40224830688. Its totient is φ = 8302694400.

The previous prime is 21545639069. The next prime is 21545639099. The reversal of 21545639090 is 9093654512.

It can be written as a sum of positive squares in 16 ways, for example, as 182601169 + 21363037921 = 13513^2 + 146161^2 .

It is not an unprimeable number, because it can be changed into a prime (21545639099) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 24455450 + ... + 24456330.

Almost surely, 2^21545639090 is an apocalyptic number.

21545639090 is a deficient number, since it is larger than the sum of its proper divisors (18679191598).

21545639090 is a wasteful number, since it uses less digits than its factorization.

21545639090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1503.

The product of its (nonzero) digits is 291600, while the sum is 44.

The spelling of 21545639090 in words is "twenty-one billion, five hundred forty-five million, six hundred thirty-nine thousand, ninety".