21263479 has 4 divisors (see below), whose sum is σ = 21284440. Its totient is φ = 21242520.

The previous prime is 21263471. The next prime is 21263497. The reversal of 21263479 is 97436212.

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 21263479 - 2³ = 21263471 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 (21263471) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8877 + ... + 11014.

It is an arithmetic number, because the mean of its divisors is an integer number (5321110).

Almost surely, 2^21263479 is an apocalyptic number.

21263479 is a deficient number, since it is larger than the sum of its proper divisors (20961).

21263479 is a wasteful number, since it uses less digits than its factorization.

21263479 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20960.

The product of its digits is 18144, while the sum is 34.

The square root of 21263479 is about 4611.2339997012. The cubic root of 21263479 is about 277.0414644232.

The spelling of 21263479 in words is "twenty-one million, two hundred sixty-three thousand, four hundred seventy-nine".