399999999961 has 2 divisors, whose sum is σ = 399999999962. Its totient is φ = 399999999960.

The previous prime is 399999999953. The next prime is 399999999977. The reversal of 399999999961 is 169999999993.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 323260473600 + 76739526361 = 568560^2 + 277019^2 .

It is a cyclic number.

It is not a de Polignac number, because 399999999961 - 2³ = 399999999953 is a prime.

It is not a weakly prime, because it can be changed into another prime (399999999911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199999999980 + 199999999981.

It is an arithmetic number, because the mean of its divisors is an integer number (199999999981).

Almost surely, 2^399999999961 is an apocalyptic number.

It is an amenable number.

399999999961 is a deficient number, since it is larger than the sum of its proper divisors (1).

399999999961 is an equidigital number, since it uses as much as digits as its factorization.

399999999961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6973568802, while the sum is 91.

It can be divided in two parts, 39 and 9999999961, that added together give a 10-th power (10000000000 = 10¹⁰).

The spelling of 399999999961 in words is "three hundred ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred sixty-one".