399981157 has 2 divisors, whose sum is σ = 399981158. Its totient is φ = 399981156.

The previous prime is 399981107. The next prime is 399981167. The reversal of 399981157 is 751189993.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 202606756 + 197374401 = 14234^2 + 14049^2 .

It is a cyclic number.

It is not a de Polignac number, because 399981157 - 2²⁷ = 265763429 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (399981107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199990578 + 199990579.

It is an arithmetic number, because the mean of its divisors is an integer number (199990579).

Almost surely, 2^399981157 is an apocalyptic number.

It is an amenable number.

399981157 is a deficient number, since it is larger than the sum of its proper divisors (1).

399981157 is an equidigital number, since it uses as much as digits as its factorization.

399981157 is an evil number, because the sum of its binary digits is even.

The product of its digits is 612360, while the sum is 52.

The square root of 399981157 is about 19999.5289194521. The cubic root of 399981157 is about 736.7947298455.

The spelling of 399981157 in words is "three hundred ninety-nine million, nine hundred eighty-one thousand, one hundred fifty-seven".