399980981 has 4 divisors (see below), whose sum is σ = 423509292. Its totient is φ = 376452672.

The previous prime is 399980957. The next prime is 399980993. The reversal of 399980981 is 189089993.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 267845956 + 132135025 = 16366^2 + 11495^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-399980981 is a prime.

It is a super-2 number, since 2×399980981² = 319969570323444722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399980681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11764130 + ... + 11764163.

It is an arithmetic number, because the mean of its divisors is an integer number (105877323).

Almost surely, 2^399980981 is an apocalyptic number.

It is an amenable number.

399980981 is a deficient number, since it is larger than the sum of its proper divisors (23528311).

399980981 is a wasteful number, since it uses less digits than its factorization.

399980981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23528310.

The product of its (nonzero) digits is 1259712, while the sum is 56.

The square root of 399980981 is about 19999.5245193480. The cubic root of 399980981 is about 736.7946217771.

The spelling of 399980981 in words is "three hundred ninety-nine million, nine hundred eighty thousand, nine hundred eighty-one".