21715019451 has 6 divisors (see below), whose sum is σ = 31366139220. Its totient is φ = 14476679628.

The previous prime is 21715019441. The next prime is 21715019453. The reversal of 21715019451 is 15491051712.

21715019451 is a `hidden beast` number, since 2 + 17 + 1 + 501 + 94 + 51 = 666.

It is not a de Polignac number, because 21715019451 - 2⁵ = 21715019419 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21715019453) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1206389961 + ... + 1206389978.

It is an arithmetic number, because the mean of its divisors is an integer number (5227689870).

Almost surely, 2^21715019451 is an apocalyptic number.

21715019451 is a deficient number, since it is larger than the sum of its proper divisors (9651119769).

21715019451 is a wasteful number, since it uses less digits than its factorization.

21715019451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2412779945 (or 2412779942 counting only the distinct ones).

The product of its (nonzero) digits is 12600, while the sum is 36.

The spelling of 21715019451 in words is "twenty-one billion, seven hundred fifteen million, nineteen thousand, four hundred fifty-one".