21072479 has 4 divisors (see below), whose sum is σ = 21081840. Its totient is φ = 21063120.

The previous prime is 21072449. The next prime is 21072481. The reversal of 21072479 is 97427012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21072479 - 2²⁰ = 20023903 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21072449) 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, 974 + ... + 6564.

It is an arithmetic number, because the mean of its divisors is an integer number (5270460).

Almost surely, 2^21072479 is an apocalyptic number.

21072479 is a deficient number, since it is larger than the sum of its proper divisors (9361).

21072479 is an equidigital number, since it uses as much as digits as its factorization.

21072479 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9360.

The product of its (nonzero) digits is 7056, while the sum is 32.

The square root of 21072479 is about 4590.4769904662. The cubic root of 21072479 is about 276.2094564552.

The spelling of 21072479 in words is "twenty-one million, seventy-two thousand, four hundred seventy-nine".