5661656021 has 8 divisors (see below), whose sum is σ = 6482085120. Its totient is φ = 4844132208.

The previous prime is 5661655997. The next prime is 5661656027. The reversal of 5661656021 is 1206561665.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 5661656021 - 2⁶ = 5661655957 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (5661656027) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 722141 + ... + 729938.

It is an arithmetic number, because the mean of its divisors is an integer number (810260640).

Almost surely, 2^5661656021 is an apocalyptic number.

It is an amenable number.

5661656021 is a deficient number, since it is larger than the sum of its proper divisors (820429099).

5661656021 is a wasteful number, since it uses less digits than its factorization.

5661656021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1452643.

The product of its (nonzero) digits is 64800, while the sum is 38.

The square root of 5661656021 is about 75243.9766426523. The cubic root of 5661656021 is about 1782.3014481155.

The spelling of 5661656021 in words is "five billion, six hundred sixty-one million, six hundred fifty-six thousand, twenty-one".