21487005 has 32 divisors (see below), whose sum is σ = 40214400. Its totient is φ = 10855296.

The previous prime is 21487001. The next prime is 21487007. The reversal of 21487005 is 50078412.

It is not a de Polignac number, because 21487005 - 2² = 21487001 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21487005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21487001) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1624 + ... + 6753.

It is an arithmetic number, because the mean of its divisors is an integer number (1256700).

Almost surely, 2^21487005 is an apocalyptic number.

It is an amenable number.

21487005 is a deficient number, since it is larger than the sum of its proper divisors (18727395).

21487005 is a wasteful number, since it uses less digits than its factorization.

21487005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8410 (or 8404 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 21487005 is about 4635.4077490551. The cubic root of 21487005 is about 278.0088545046.

The spelling of 21487005 in words is "twenty-one million, four hundred eighty-seven thousand, five".