1656447661 has 4 divisors (see below), whose sum is σ = 1807033824. Its totient is φ = 1505861500.

The previous prime is 1656447647. The next prime is 1656447671. The reversal of 1656447661 is 1667446561.

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 not a de Polignac number, because 1656447661 - 2⁵ = 1656447629 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 (1656447641) 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 3 ways as a sum of consecutive naturals, for example, 75293065 + ... + 75293086.

It is an arithmetic number, because the mean of its divisors is an integer number (451758456).

Almost surely, 2^1656447661 is an apocalyptic number.

1656447661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1656447661 is a deficient number, since it is larger than the sum of its proper divisors (150586163).

1656447661 is a wasteful number, since it uses less digits than its factorization.

1656447661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150586162.

The product of its digits is 725760, while the sum is 46.

The square root of 1656447661 is about 40699.4798615412. The cubic root of 1656447661 is about 1183.2029378415.

The spelling of 1656447661 in words is "one billion, six hundred fifty-six million, four hundred forty-seven thousand, six hundred sixty-one".