21240576816 has 20 divisors (see below), whose sum is σ = 54871490232. Its totient is φ = 7080192256.

The previous prime is 21240576811. The next prime is 21240576827. The reversal of 21240576816 is 61867504212.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21240576811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 221255961 + ... + 221256056.

Almost surely, 2^21240576816 is an apocalyptic number.

It is an amenable number.

21240576816 is an abundant number, since it is smaller than the sum of its proper divisors (33630913416).

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

21240576816 is a wasteful number, since it uses less digits than its factorization.

21240576816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 442512028 (or 442512022 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 42.

The spelling of 21240576816 in words is "twenty-one billion, two hundred forty million, five hundred seventy-six thousand, eight hundred sixteen".