1656651661 has 4 divisors (see below), whose sum is σ = 1893316192. Its totient is φ = 1419987132.

The previous prime is 1656651631. The next prime is 1656651671. The reversal of 1656651661 is 1661566561.

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.

It is a cyclic number.

It is not a de Polignac number, because 1656651661 - 2⁹ = 1656651149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1656651631) 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, 118332255 + ... + 118332268.

It is an arithmetic number, because the mean of its divisors is an integer number (473329048).

Almost surely, 2^1656651661 is an apocalyptic number.

It is an amenable number.

1656651661 is a deficient number, since it is larger than the sum of its proper divisors (236664531).

1656651661 is an equidigital number, since it uses as much as digits as its factorization.

1656651661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 236664530.

The product of its digits is 194400, while the sum is 43.

The square root of 1656651661 is about 40701.9859589185. The cubic root of 1656651661 is about 1183.2515083451.

The spelling of 1656651661 in words is "one billion, six hundred fifty-six million, six hundred fifty-one thousand, six hundred sixty-one".