21780311524 has 12 divisors (see below), whose sum is σ = 38117810304. Its totient is φ = 10889508584.

The previous prime is 21780311513. The next prime is 21780311533. The reversal of 21780311524 is 42511308712.

It is a self number, because there is not a number n which added to its sum of digits gives 21780311524.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 81664 + ... + 224119.

It is an arithmetic number, because the mean of its divisors is an integer number (3176484192).

Almost surely, 2^21780311524 is an apocalyptic number.

It is an amenable number.

21780311524 is a deficient number, since it is larger than the sum of its proper divisors (16337498780).

21780311524 is a wasteful number, since it uses less digits than its factorization.

21780311524 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 323594 (or 323592 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 34.

The spelling of 21780311524 in words is "twenty-one billion, seven hundred eighty million, three hundred eleven thousand, five hundred twenty-four".