56001661 has 4 divisors (see below), whose sum is σ = 56023324. Its totient is φ = 55980000.

The previous prime is 56001653. The next prime is 56001691. The reversal of 56001661 is 16610065.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16610065 = 5 ⋅3322013.

It can be written as a sum of positive squares in 2 ways, for example, as 15920100 + 40081561 = 3990^2 + 6331^2 .

It is a cyclic number.

It is not a de Polignac number, because 56001661 - 2³ = 56001653 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 (56001601) 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, 6330 + ... + 12331.

It is an arithmetic number, because the mean of its divisors is an integer number (14005831).

Almost surely, 2^56001661 is an apocalyptic number.

It is an amenable number.

56001661 is a deficient number, since it is larger than the sum of its proper divisors (21663).

56001661 is a wasteful number, since it uses less digits than its factorization.

56001661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21662.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 56001661 is about 7483.4257529557. The cubic root of 56001661 is about 382.5900191108.

The spelling of 56001661 in words is "fifty-six million, one thousand, six hundred sixty-one".