21272515 has 16 divisors (see below), whose sum is σ = 28810080. Its totient is φ = 14936320.

The previous prime is 21272507. The next prime is 21272527. The reversal of 21272515 is 51527212.

It is not a de Polignac number, because 21272515 - 2³ = 21272507 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21272515.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5074 + ... + 8263.

It is an arithmetic number, because the mean of its divisors is an integer number (1800630).

Almost surely, 2^21272515 is an apocalyptic number.

21272515 is a deficient number, since it is larger than the sum of its proper divisors (7537565).

21272515 is a wasteful number, since it uses less digits than its factorization.

21272515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13382.

The product of its digits is 1400, while the sum is 25.

The square root of 21272515 is about 4612.2136767500. The cubic root of 21272515 is about 277.0807021565.

Adding to 21272515 its reverse (51527212), we get a palindrome (72799727).

It can be divided in two parts, 212 and 72515, that added together give a palindrome (72727).

The spelling of 21272515 in words is "twenty-one million, two hundred seventy-two thousand, five hundred fifteen".