1656691491 has 64 divisors (see below), whose sum is σ = 2954362880. Its totient is φ = 801083520.

The previous prime is 1656691489. The next prime is 1656691501. The reversal of 1656691491 is 1941966561.

It is not a de Polignac number, because 1656691491 - 2¹ = 1656691489 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1656691491.

It is not an unprimeable number, because it can be changed into a prime (1656691411) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 155646 + ... + 165948.

It is an arithmetic number, because the mean of its divisors is an integer number (46161920).

Almost surely, 2^1656691491 is an apocalyptic number.

1656691491 is a deficient number, since it is larger than the sum of its proper divisors (1297671389).

1656691491 is a wasteful number, since it uses less digits than its factorization.

1656691491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10376.

The product of its digits is 349920, while the sum is 48.

The square root of 1656691491 is about 40702.4752441421. The cubic root of 1656691491 is about 1183.2609910325.

The spelling of 1656691491 in words is "one billion, six hundred fifty-six million, six hundred ninety-one thousand, four hundred ninety-one".