21231965 has 16 divisors (see below), whose sum is σ = 26307840. Its totient is φ = 16441920.

The previous prime is 21231941. The next prime is 21231971. The reversal of 21231965 is 56913212.

It is not a de Polignac number, because 21231965 - 2¹⁰ = 21230941 is a prime.

It is a super-2 number, since 2×21231965² = 901592675522450, which contains 22 as substring.

It is a congruent 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, 19916 + ... + 20954.

It is an arithmetic number, because the mean of its divisors is an integer number (1644240).

Almost surely, 2^21231965 is an apocalyptic number.

It is an amenable number.

21231965 is a deficient number, since it is larger than the sum of its proper divisors (5075875).

21231965 is a wasteful number, since it uses less digits than its factorization.

21231965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1172.

The product of its digits is 3240, while the sum is 29.

The square root of 21231965 is about 4607.8156430135. The cubic root of 21231965 is about 276.9045316502.

The spelling of 21231965 in words is "twenty-one million, two hundred thirty-one thousand, nine hundred sixty-five".