21372115 has 4 divisors (see below), whose sum is σ = 25646544. Its totient is φ = 17097688.

The previous prime is 21372103. The next prime is 21372133. The reversal of 21372115 is 51127312.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21372115 - 2¹⁷ = 21241043 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2137207 + ... + 2137216.

It is an arithmetic number, because the mean of its divisors is an integer number (6411636).

Almost surely, 2^21372115 is an apocalyptic number.

21372115 is a deficient number, since it is larger than the sum of its proper divisors (4274429).

21372115 is an equidigital number, since it uses as much as digits as its factorization.

21372115 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4274428.

The product of its digits is 420, while the sum is 22.

The square root of 21372115 is about 4622.9984858315. The cubic root of 21372115 is about 277.5124686657.

Adding to 21372115 its reverse (51127312), we get a palindrome (72499427).

The spelling of 21372115 in words is "twenty-one million, three hundred seventy-two thousand, one hundred fifteen".