1390681 has 2 divisors, whose sum is σ = 1390682. Its totient is φ = 1390680.

The previous prime is 1390643. The next prime is 1390693. The reversal of 1390681 is 1860931.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1243225 + 147456 = 1115^2 + 384^2 .

It is a cyclic number.

It is not a de Polignac number, because 1390681 - 2¹¹ = 1388633 is a prime.

It is a super-2 number, since 2×1390681² = 3867987287522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1390601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 695340 + 695341.

It is an arithmetic number, because the mean of its divisors is an integer number (695341).

2^1390681 is an apocalyptic number.

It is an amenable number.

1390681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1390681 is an equidigital number, since it uses as much as digits as its factorization.

1390681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 1390681 is about 1179.2713852206. The cubic root of 1390681 is about 111.6201256510.

The spelling of 1390681 in words is "one million, three hundred ninety thousand, six hundred eighty-one".