390571981 has 2 divisors, whose sum is σ = 390571982. Its totient is φ = 390571980.

The previous prime is 390571969. The next prime is 390572009. The reversal of 390571981 is 189175093.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 389707081 + 864900 = 19741^2 + 930^2 .

It is an emirp because it is prime and its reverse (189175093) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-390571981 is a prime.

It is a super-2 number, since 2×390571981² = 305092944684528722, which contains 22 as substring.

It is a nialpdrome in base 12.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (390571921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195285990 + 195285991.

It is an arithmetic number, because the mean of its divisors is an integer number (195285991).

Almost surely, 2^390571981 is an apocalyptic number.

It is an amenable number.

390571981 is a deficient number, since it is larger than the sum of its proper divisors (1).

390571981 is an equidigital number, since it uses as much as digits as its factorization.

390571981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 68040, while the sum is 43.

The square root of 390571981 is about 19762.8940441424. The cubic root of 390571981 is about 730.9713603109.

The spelling of 390571981 in words is "three hundred ninety million, five hundred seventy-one thousand, nine hundred eighty-one".