21439605 has 16 divisors (see below), whose sum is σ = 37422144. Its totient is φ = 10394880.

The previous prime is 21439577. The next prime is 21439633. The reversal of 21439605 is 50693412.

It is an interprime number because it is at equal distance from previous prime (21439577) and next prime (21439633).

It is not a de Polignac number, because 21439605 - 2¹² = 21435509 is a prime.

It is a congruent number.

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, 64804 + ... + 65133.

It is an arithmetic number, because the mean of its divisors is an integer number (2338884).

Almost surely, 2^21439605 is an apocalyptic number.

It is an amenable number.

21439605 is a deficient number, since it is larger than the sum of its proper divisors (15982539).

21439605 is a wasteful number, since it uses less digits than its factorization.

21439605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129956.

The product of its (nonzero) digits is 6480, while the sum is 30.

The square root of 21439605 is about 4630.2921074161. The cubic root of 21439605 is about 277.8042762573.

The spelling of 21439605 in words is "twenty-one million, four hundred thirty-nine thousand, six hundred five".