1320990691 has 4 divisors (see below), whose sum is σ = 1321626952. Its totient is φ = 1320354432.

The previous prime is 1320990677. The next prime is 1320990701. The reversal of 1320990691 is 1960990231.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1960990231 = 27361 ⋅71671.

It is a cyclic number.

It is not a de Polignac number, because 1320990691 - 2¹⁷ = 1320859619 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1320990611) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 315006 + ... + 319171.

It is an arithmetic number, because the mean of its divisors is an integer number (330406738).

Almost surely, 2^1320990691 is an apocalyptic number.

1320990691 is a deficient number, since it is larger than the sum of its proper divisors (636261).

1320990691 is an equidigital number, since it uses as much as digits as its factorization.

1320990691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 636260.

The product of its (nonzero) digits is 26244, while the sum is 40.

The square root of 1320990691 is about 36345.4356281501. The cubic root of 1320990691 is about 1097.2356736011.

The spelling of 1320990691 in words is "one billion, three hundred twenty million, nine hundred ninety thousand, six hundred ninety-one".