1561956591651 has 16 divisors (see below), whose sum is σ = 2097088519680. Its totient is φ = 1034074913760.

The previous prime is 1561956591563. The next prime is 1561956591659.

1561956591651 is nontrivially palindromic in base 10.

It is a de Polignac number, because none of the positive numbers 2^k-1561956591651 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1561956591659) 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, 695436 + ... + 1899353.

It is an arithmetic number, because the mean of its divisors is an integer number (131068032480).

Almost surely, 2^{1561956591651} is an apocalyptic number.

1561956591651 is a deficient number, since it is larger than the sum of its proper divisors (535131928029).

1561956591651 is a wasteful number, since it uses less digits than its factorization.

1561956591651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2596186.

The product of its digits is 10935000, while the sum is 60.

The spelling of 1561956591651 in words is "one trillion, five hundred sixty-one billion, nine hundred fifty-six million, five hundred ninety-one thousand, six hundred fifty-one".