20215291 has 4 divisors (see below), whose sum is σ = 20912400. Its totient is φ = 19518184.

The previous prime is 20215267. The next prime is 20215301. The reversal of 20215291 is 19251202.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20215291 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20215211) 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, 348511 + ... + 348568.

It is an arithmetic number, because the mean of its divisors is an integer number (5228100).

Almost surely, 2^20215291 is an apocalyptic number.

20215291 is a deficient number, since it is larger than the sum of its proper divisors (697109).

20215291 is an equidigital number, since it uses as much as digits as its factorization.

20215291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 697108.

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

The square root of 20215291 is about 4496.1417904688. The cubic root of 20215291 is about 272.4122703871.

Adding to 20215291 its reverse (19251202), we get a palindrome (39466493).

The spelling of 20215291 in words is "twenty million, two hundred fifteen thousand, two hundred ninety-one".