21705903 has 12 divisors (see below), whose sum is σ = 31426720. Its totient is φ = 14436576.

The previous prime is 21705899. The next prime is 21705947. The reversal of 21705903 is 30950712.

21705903 is a `hidden beast` number, since 2 + 1 + 70 + 590 + 3 = 666.

It is not a de Polignac number, because 21705903 - 2² = 21705899 is a prime.

It is a super-2 number, since 2×21705903² = 942292450090818, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21705973) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1563 + ... + 6771.

Almost surely, 2^21705903 is an apocalyptic number.

21705903 is a deficient number, since it is larger than the sum of its proper divisors (9720817).

21705903 is a wasteful number, since it uses less digits than its factorization.

21705903 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5678 (or 5675 counting only the distinct ones).

The product of its (nonzero) digits is 1890, while the sum is 27.

The square root of 21705903 is about 4658.9594331782. The cubic root of 21705903 is about 278.9497346529.

The spelling of 21705903 in words is "twenty-one million, seven hundred five thousand, nine hundred three".