661072157 has 2 divisors, whose sum is σ = 661072158. Its totient is φ = 661072156.

The previous prime is 661072147. The next prime is 661072177. The reversal of 661072157 is 751270166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 373803556 + 287268601 = 19334^2 + 16949^2 .

It is a cyclic number.

It is not a de Polignac number, because 661072157 - 2¹⁰ = 661071133 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661072147) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330536078 + 330536079.

It is an arithmetic number, because the mean of its divisors is an integer number (330536079).

Almost surely, 2^661072157 is an apocalyptic number.

It is an amenable number.

661072157 is a deficient number, since it is larger than the sum of its proper divisors (1).

661072157 is an equidigital number, since it uses as much as digits as its factorization.

661072157 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17640, while the sum is 35.

The square root of 661072157 is about 25711.3235170810. The cubic root of 661072157 is about 871.1299700642.

The spelling of 661072157 in words is "six hundred sixty-one million, seventy-two thousand, one hundred fifty-seven".