20215921 has 8 divisors (see below), whose sum is σ = 22096800. Its totient is φ = 18342240.

The previous prime is 20215883. The next prime is 20215967. The reversal of 20215921 is 12951202.

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 20215921 - 2¹¹ = 20213873 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20215892 and 20215901.

It is not an unprimeable number, because it can be changed into a prime (20215991) 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, 5325 + ... + 8293.

It is an arithmetic number, because the mean of its divisors is an integer number (2762100).

Almost surely, 2^20215921 is an apocalyptic number.

It is an amenable number.

20215921 is a deficient number, since it is larger than the sum of its proper divisors (1880879).

20215921 is a wasteful number, since it uses less digits than its factorization.

20215921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3599.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 20215921 is about 4496.2118499911. The cubic root of 20215921 is about 272.4151002243.

The spelling of 20215921 in words is "twenty million, two hundred fifteen thousand, nine hundred twenty-one".