1390531981 has 2 divisors, whose sum is σ = 1390531982. Its totient is φ = 1390531980.

The previous prime is 1390531963. The next prime is 1390532023. The reversal of 1390531981 is 1891350931.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1300756356 + 89775625 = 36066^2 + 9475^2 .

It is a cyclic number.

It is not a de Polignac number, because 1390531981 - 2¹⁷ = 1390400909 is a prime.

It is a super-2 number, since 2×1390531981² = 3867158380367568722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1390531481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 695265990 + 695265991.

It is an arithmetic number, because the mean of its divisors is an integer number (695265991).

Almost surely, 2^1390531981 is an apocalyptic number.

It is an amenable number.

1390531981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1390531981 is an equidigital number, since it uses as much as digits as its factorization.

1390531981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 29160, while the sum is 40.

The square root of 1390531981 is about 37289.8375029981. The cubic root of 1390531981 is about 1116.1613860828.

The spelling of 1390531981 in words is "one billion, three hundred ninety million, five hundred thirty-one thousand, nine hundred eighty-one".