399511561 has 2 divisors, whose sum is σ = 399511562. Its totient is φ = 399511560.

The previous prime is 399511547. The next prime is 399511573. The reversal of 399511561 is 165115993.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 352725961 + 46785600 = 18781^2 + 6840^2 .

It is a cyclic number.

It is not a de Polignac number, because 399511561 - 2²⁵ = 365957129 is a prime.

It is not a weakly prime, because it can be changed into another prime (399511061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199755780 + 199755781.

It is an arithmetic number, because the mean of its divisors is an integer number (199755781).

Almost surely, 2^399511561 is an apocalyptic number.

It is an amenable number.

399511561 is a deficient number, since it is larger than the sum of its proper divisors (1).

399511561 is an equidigital number, since it uses as much as digits as its factorization.

399511561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36450, while the sum is 40.

The square root of 399511561 is about 19987.7852950246. The cubic root of 399511561 is about 736.5062734643.

The spelling of 399511561 in words is "three hundred ninety-nine million, five hundred eleven thousand, five hundred sixty-one".