21051505644 has 48 divisors (see below), whose sum is σ = 54328363488. Its totient is φ = 6302320128.

The previous prime is 21051505621. The next prime is 21051505661. The reversal of 21051505644 is 44650515012.

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, 1817817 + ... + 1829360.

It is an arithmetic number, because the mean of its divisors is an integer number (1131840906).

Almost surely, 2^21051505644 is an apocalyptic number.

It is an amenable number.

21051505644 is an abundant number, since it is smaller than the sum of its proper divisors (33276857844).

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

21051505644 is a wasteful number, since it uses less digits than its factorization.

21051505644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3647234 (or 3647232 counting only the distinct ones).

The product of its (nonzero) digits is 24000, while the sum is 33.

The spelling of 21051505644 in words is "twenty-one billion, fifty-one million, five hundred five thousand, six hundred forty-four".