21487605 has 16 divisors (see below), whose sum is σ = 34817280. Its totient is φ = 11314368.

The previous prime is 21487597. The next prime is 21487667. The reversal of 21487605 is 50678412.

It is not a de Polignac number, because 21487605 - 2³ = 21487597 is a prime.

It is a Curzon number.

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, 7882 + ... + 10251.

It is an arithmetic number, because the mean of its divisors is an integer number (2176080).

Almost surely, 2^21487605 is an apocalyptic number.

It is an amenable number.

21487605 is a deficient number, since it is larger than the sum of its proper divisors (13329675).

21487605 is a wasteful number, since it uses less digits than its factorization.

21487605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18220.

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 21487605 is about 4635.4724678289. The cubic root of 21487605 is about 278.0114421735.

The spelling of 21487605 in words is "twenty-one million, four hundred eighty-seven thousand, six hundred five".