20151500921 has 2 divisors, whose sum is σ = 20151500922. Its totient is φ = 20151500920.

The previous prime is 20151500827. The next prime is 20151500939. The reversal of 20151500921 is 12900515102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16037689600 + 4113811321 = 126640^2 + 64139^2 .

It is a cyclic number.

It is not a de Polignac number, because 20151500921 - 2²² = 20147306617 is a prime.

It is not a weakly prime, because it can be changed into another prime (20151500981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10075750460 + 10075750461.

It is an arithmetic number, because the mean of its divisors is an integer number (10075750461).

Almost surely, 2^20151500921 is an apocalyptic number.

It is an amenable number.

20151500921 is a deficient number, since it is larger than the sum of its proper divisors (1).

20151500921 is an equidigital number, since it uses as much as digits as its factorization.

20151500921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 900, while the sum is 26.

The spelling of 20151500921 in words is "twenty billion, one hundred fifty-one million, five hundred thousand, nine hundred twenty-one".