21957965 has 8 divisors (see below), whose sum is σ = 27899640. Its totient is φ = 16532992.

The previous prime is 21957961. The next prime is 21957973. The reversal of 21957965 is 56975912.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 6165289 + 15792676 = 2483^2 + 3974^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21957965 - 2² = 21957961 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21957961) 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 7 ways as a sum of consecutive naturals, for example, 129080 + ... + 129249.

It is an arithmetic number, because the mean of its divisors is an integer number (3487455).

Almost surely, 2^21957965 is an apocalyptic number.

It is an amenable number.

21957965 is a deficient number, since it is larger than the sum of its proper divisors (5941675).

21957965 is a wasteful number, since it uses less digits than its factorization.

21957965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 258351.

The product of its digits is 170100, while the sum is 44.

The square root of 21957965 is about 4685.9326713046. The cubic root of 21957965 is about 280.0253590978.

It can be divided in two parts, 21957 and 965, that added together give a palindrome (22922).

The spelling of 21957965 in words is "twenty-one million, nine hundred fifty-seven thousand, nine hundred sixty-five".