21971705 has 16 divisors (see below), whose sum is σ = 31173120. Its totient is φ = 14546112.

The previous prime is 21971687. The next prime is 21971707. The reversal of 21971705 is 50717912.

It is not a de Polignac number, because 21971705 - 2²² = 17777401 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21971707) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9809 + ... + 11838.

It is an arithmetic number, because the mean of its divisors is an integer number (1948320).

Almost surely, 2^21971705 is an apocalyptic number.

It is an amenable number.

21971705 is a deficient number, since it is larger than the sum of its proper divisors (9201415).

21971705 is a wasteful number, since it uses less digits than its factorization.

21971705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21688.

The product of its (nonzero) digits is 4410, while the sum is 32.

The square root of 21971705 is about 4687.3985322351. The cubic root of 21971705 is about 280.0837547064.

The spelling of 21971705 in words is "twenty-one million, nine hundred seventy-one thousand, seven hundred five".