156666952021 has 2 divisors, whose sum is σ = 156666952022. Its totient is φ = 156666952020.

The previous prime is 156666951983. The next prime is 156666952069. The reversal of 156666952021 is 120259666651.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 91430640625 + 65236311396 = 302375^2 + 255414^2 .

It is a cyclic number.

It is not a de Polignac number, because 156666952021 - 2⁹ = 156666951509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (156666952081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 78333476010 + 78333476011.

It is an arithmetic number, because the mean of its divisors is an integer number (78333476011).

Almost surely, 2^156666952021 is an apocalyptic number.

It is an amenable number.

156666952021 is a deficient number, since it is larger than the sum of its proper divisors (1).

156666952021 is an equidigital number, since it uses as much as digits as its factorization.

156666952021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1166400, while the sum is 49.

The spelling of 156666952021 in words is "one hundred fifty-six billion, six hundred sixty-six million, nine hundred fifty-two thousand, twenty-one".