1656536561 has 4 divisors (see below), whose sum is σ = 1657130352. Its totient is φ = 1655942772.

The previous prime is 1656536549. The next prime is 1656536587. The reversal of 1656536561 is 1656356561.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1656356561 = 37021 ⋅44741.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1656536561 is a prime.

It is a super-2 number, since 2×1656536561² = 5488226755859413442, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1656536461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 292691 + ... + 298296.

It is an arithmetic number, because the mean of its divisors is an integer number (414282588).

Almost surely, 2^1656536561 is an apocalyptic number.

It is an amenable number.

1656536561 is a deficient number, since it is larger than the sum of its proper divisors (593791).

1656536561 is an equidigital number, since it uses as much as digits as its factorization.

1656536561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 593790.

The product of its digits is 486000, while the sum is 44.

The square root of 1656536561 is about 40700.5719984376. The cubic root of 1656536561 is about 1183.2241045953.

The spelling of 1656536561 in words is "one billion, six hundred fifty-six million, five hundred thirty-six thousand, five hundred sixty-one".