21512479 has 4 divisors (see below), whose sum is σ = 21529584. Its totient is φ = 21495376.

The previous prime is 21512473. The next prime is 21512483. The reversal of 21512479 is 97421512.

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 21512479 - 2⁹ = 21511967 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21512479.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21512473) 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, 6502 + ... + 9235.

It is an arithmetic number, because the mean of its divisors is an integer number (5382396).

Almost surely, 2^21512479 is an apocalyptic number.

21512479 is a deficient number, since it is larger than the sum of its proper divisors (17105).

21512479 is a wasteful number, since it uses less digits than its factorization.

21512479 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17104.

The product of its digits is 5040, while the sum is 31.

The square root of 21512479 is about 4638.1546977219. The cubic root of 21512479 is about 278.1186759325.

The spelling of 21512479 in words is "twenty-one million, five hundred twelve thousand, four hundred seventy-nine".