21404705 has 16 divisors (see below), whose sum is σ = 29472384. Its totient is φ = 14618880.

The previous prime is 21404689. The next prime is 21404729. The reversal of 21404705 is 50740412.

It is not a de Polignac number, because 21404705 - 2⁴ = 21404689 is a prime.

It is a super-2 number, since 2×21404705² = 916322792274050, which contains 22 as substring.

It is a Duffinian 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, 8825 + ... + 10985.

It is an arithmetic number, because the mean of its divisors is an integer number (1842024).

Almost surely, 2^21404705 is an apocalyptic number.

It is an amenable number.

21404705 is a deficient number, since it is larger than the sum of its proper divisors (8067679).

21404705 is a wasteful number, since it uses less digits than its factorization.

21404705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2456.

The product of its (nonzero) digits is 1120, while the sum is 23.

The square root of 21404705 is about 4626.5219117605. The cubic root of 21404705 is about 277.6534551515.

The spelling of 21404705 in words is "twenty-one million, four hundred four thousand, seven hundred five".