390909681 has 12 divisors (see below), whose sum is σ = 564914740. Its totient is φ = 260483040.

The previous prime is 390909653. The next prime is 390909731. The reversal of 390909681 is 186909093.

It can be written as a sum of positive squares in 2 ways, for example, as 248346081 + 142563600 = 15759^2 + 11940^2 .

It is not a de Polignac number, because 390909681 - 2¹¹ = 390907633 is a prime.

It is a super-2 number, since 2×390909681² = 305620757399043522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (390909581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12411 + ... + 30591.

Almost surely, 2^390909681 is an apocalyptic number.

It is an amenable number.

390909681 is a deficient number, since it is larger than the sum of its proper divisors (174005059).

390909681 is a wasteful number, since it uses less digits than its factorization.

390909681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20576 (or 20573 counting only the distinct ones).

The product of its (nonzero) digits is 104976, while the sum is 45.

The square root of 390909681 is about 19771.4359873025. The cubic root of 390909681 is about 731.1819727206.

The spelling of 390909681 in words is "three hundred ninety million, nine hundred nine thousand, six hundred eighty-one".