399199664581 has 2 divisors, whose sum is σ = 399199664582. Its totient is φ = 399199664580.

The previous prime is 399199664557. The next prime is 399199664593. The reversal of 399199664581 is 185466991993.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 280719828900 + 118479835681 = 529830^2 + 344209^2 .

It is a cyclic number.

It is not a de Polignac number, because 399199664581 - 2³³ = 390609729989 is a prime.

It is a super-2 number, since 2×399199664581² (a number of 24 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 399199664581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (399199665581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199599832290 + 199599832291.

It is an arithmetic number, because the mean of its divisors is an integer number (199599832291).

Almost surely, 2^399199664581 is an apocalyptic number.

It is an amenable number.

399199664581 is a deficient number, since it is larger than the sum of its proper divisors (1).

399199664581 is an equidigital number, since it uses as much as digits as its factorization.

399199664581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 113374080, while the sum is 70.

The spelling of 399199664581 in words is "three hundred ninety-nine billion, one hundred ninety-nine million, six hundred sixty-four thousand, five hundred eighty-one".