21971205 has 12 divisors (see below), whose sum is σ = 38083500. Its totient is φ = 11717952.

The previous prime is 21971197. The next prime is 21971221. The reversal of 21971205 is 50217912.

It can be written as a sum of positive squares in 2 ways, for example, as 11512449 + 10458756 = 3393^2 + 3234^2 .

It is not a de Polignac number, because 21971205 - 2³ = 21971197 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 244080 + ... + 244169.

It is an arithmetic number, because the mean of its divisors is an integer number (3173625).

Almost surely, 2^21971205 is an apocalyptic number.

It is an amenable number.

21971205 is a deficient number, since it is larger than the sum of its proper divisors (16112295).

21971205 is a wasteful number, since it uses less digits than its factorization.

21971205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 488260 (or 488257 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 27.

The square root of 21971205 is about 4687.3451974439. The cubic root of 21971205 is about 280.0816301111.

The spelling of 21971205 in words is "twenty-one million, nine hundred seventy-one thousand, two hundred five".