155640857 has 2 divisors, whose sum is σ = 155640858. Its totient is φ = 155640856.

The previous prime is 155640811. The next prime is 155640869. The reversal of 155640857 is 758046551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 146991376 + 8649481 = 12124^2 + 2941^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-155640857 is a prime.

It is not a weakly prime, because it can be changed into another prime (155640887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77820428 + 77820429.

It is an arithmetic number, because the mean of its divisors is an integer number (77820429).

Almost surely, 2^155640857 is an apocalyptic number.

It is an amenable number.

155640857 is a deficient number, since it is larger than the sum of its proper divisors (1).

155640857 is an equidigital number, since it uses as much as digits as its factorization.

155640857 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 168000, while the sum is 41.

The square root of 155640857 is about 12475.6104860644. The cubic root of 155640857 is about 537.9078362783.

The spelling of 155640857 in words is "one hundred fifty-five million, six hundred forty thousand, eight hundred fifty-seven".