681660157 has 2 divisors, whose sum is σ = 681660158. Its totient is φ = 681660156.

The previous prime is 681660143. The next prime is 681660179. The reversal of 681660157 is 751066186.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 617323716 + 64336441 = 24846^2 + 8021^2 .

It is a cyclic number.

It is not a de Polignac number, because 681660157 - 2¹⁵ = 681627389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (681660127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340830078 + 340830079.

It is an arithmetic number, because the mean of its divisors is an integer number (340830079).

Almost surely, 2^681660157 is an apocalyptic number.

It is an amenable number.

681660157 is a deficient number, since it is larger than the sum of its proper divisors (1).

681660157 is an equidigital number, since it uses as much as digits as its factorization.

681660157 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 60480, while the sum is 40.

The square root of 681660157 is about 26108.6222731112. The cubic root of 681660157 is about 880.0809829914.

The spelling of 681660157 in words is "six hundred eighty-one million, six hundred sixty thousand, one hundred fifty-seven".