21365021 has 8 divisors (see below), whose sum is σ = 22316640. Its totient is φ = 20433168.

The previous prime is 21365017. The next prime is 21365033. The reversal of 21365021 is 12056312.

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 21365021 - 2² = 21365017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21364984 and 21365002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21365041) 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, 2711 + ... + 7076.

It is an arithmetic number, because the mean of its divisors is an integer number (2789580).

Almost surely, 2^21365021 is an apocalyptic number.

It is an amenable number.

21365021 is a deficient number, since it is larger than the sum of its proper divisors (951619).

21365021 is an equidigital number, since it uses as much as digits as its factorization.

21365021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9883.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 21365021 is about 4622.2311711986. The cubic root of 21365021 is about 277.4817605630.

The spelling of 21365021 in words is "twenty-one million, three hundred sixty-five thousand, twenty-one".