21655793 has 8 divisors (see below), whose sum is σ = 22219560. Its totient is φ = 21098880.

The previous prime is 21655787. The next prime is 21655813. The reversal of 21655793 is 39755612.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 3139984 + 18515809 = 1772^2 + 4303^2 .

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 21655793 - 2⁶ = 21655729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21655723) 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, 5021 + ... + 8277.

It is an arithmetic number, because the mean of its divisors is an integer number (2777445).

Almost surely, 2^21655793 is an apocalyptic number.

It is an amenable number.

21655793 is a deficient number, since it is larger than the sum of its proper divisors (563767).

21655793 is a wasteful number, since it uses less digits than its factorization.

21655793 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3427.

The product of its digits is 56700, while the sum is 38.

The square root of 21655793 is about 4653.5785155083. The cubic root of 21655793 is about 278.7349091953.

The spelling of 21655793 in words is "twenty-one million, six hundred fifty-five thousand, seven hundred ninety-three".