21479391 has 8 divisors (see below), whose sum is σ = 31821360. Its totient is φ = 14319576.

The previous prime is 21479377. The next prime is 21479407. The reversal of 21479391 is 19397412.

It is not a de Polignac number, because 21479391 - 2¹¹ = 21477343 is a prime.

It is a super-2 number, since 2×21479391² = 922728475461762, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21479371) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 397740 + ... + 397793.

It is an arithmetic number, because the mean of its divisors is an integer number (3977670).

Almost surely, 2^21479391 is an apocalyptic number.

21479391 is a deficient number, since it is larger than the sum of its proper divisors (10341969).

21479391 is an equidigital number, since it uses as much as digits as its factorization.

21479391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 795542 (or 795536 counting only the distinct ones).

The product of its digits is 13608, while the sum is 36.

The square root of 21479391 is about 4634.5863893124. The cubic root of 21479391 is about 277.9760128019.

The spelling of 21479391 in words is "twenty-one million, four hundred seventy-nine thousand, three hundred ninety-one".