1390891561 has 16 divisors (see below), whose sum is σ = 1516242240. Its totient is φ = 1271574720.

The previous prime is 1390891549. The next prime is 1390891571. The reversal of 1390891561 is 1651980931.

It is a cyclic number.

It is not a de Polignac number, because 1390891561 - 2⁵ = 1390891529 is a prime.

It is a super-2 number, since 2×1390891561² = 3869158668922033442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1390891571) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50106 + ... + 72748.

It is an arithmetic number, because the mean of its divisors is an integer number (94765140).

Almost surely, 2^1390891561 is an apocalyptic number.

It is an amenable number.

1390891561 is a deficient number, since it is larger than the sum of its proper divisors (125350679).

1390891561 is a wasteful number, since it uses less digits than its factorization.

1390891561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22776.

The product of its (nonzero) digits is 58320, while the sum is 43.

The square root of 1390891561 is about 37294.6586121927. The cubic root of 1390891561 is about 1116.2575878067.

The spelling of 1390891561 in words is "one billion, three hundred ninety million, eight hundred ninety-one thousand, five hundred sixty-one".