21761971 has 12 divisors (see below), whose sum is σ = 27338416. Its totient is φ = 16956720.

The previous prime is 21761947. The next prime is 21761983. The reversal of 21761971 is 17916712.

21761971 = T₇₁₃ + T₇₁₄ + ... + T₇₈₉.

It is not a de Polignac number, because 21761971 - 2⁹ = 21761459 is a prime.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21761941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12000 + ... + 13693.

Almost surely, 2^21761971 is an apocalyptic number.

21761971 is a deficient number, since it is larger than the sum of its proper divisors (5576445).

21761971 is a wasteful number, since it uses less digits than its factorization.

21761971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25722 (or 25711 counting only the distinct ones).

The product of its digits is 5292, while the sum is 34.

The square root of 21761971 is about 4664.9727759120. The cubic root of 21761971 is about 279.1897109464.

The spelling of 21761971 in words is "twenty-one million, seven hundred sixty-one thousand, nine hundred seventy-one".