21971775 has 24 divisors (see below), whose sum is σ = 41517184. Its totient is φ = 10044000.

The previous prime is 21971749. The next prime is 21971783. The reversal of 21971775 is 57717912.

It is not a de Polignac number, because 21971775 - 2⁶ = 21971711 is a prime.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20401 + ... + 21450.

Almost surely, 2^21971775 is an apocalyptic number.

21971775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21971775 is a deficient number, since it is larger than the sum of its proper divisors (19545409).

21971775 is a wasteful number, since it uses less digits than its factorization.

21971775 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41871 (or 41866 counting only the distinct ones).

The product of its digits is 30870, while the sum is 39.

The square root of 21971775 is about 4687.4059990575. The cubic root of 21971775 is about 280.0840521471.

The spelling of 21971775 in words is "twenty-one million, nine hundred seventy-one thousand, seven hundred seventy-five".