21713969 has 8 divisors (see below), whose sum is σ = 22348872. Its totient is φ = 21084160.

The previous prime is 21713959. The next prime is 21713971. The reversal of 21713969 is 96931712.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 664225 + 21049744 = 815^2 + 4588^2 .

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 21713969 - 2²⁴ = 4936753 is a prime.

It is a super-2 number, since 2×21713969² = 942992899465922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21713929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8417 + ... + 10689.

It is an arithmetic number, because the mean of its divisors is an integer number (2793609).

Almost surely, 2^21713969 is an apocalyptic number.

It is an amenable number.

21713969 is a deficient number, since it is larger than the sum of its proper divisors (634903).

21713969 is a wasteful number, since it uses less digits than its factorization.

21713969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2547.

The product of its digits is 20412, while the sum is 38.

The square root of 21713969 is about 4659.8249967139. The cubic root of 21713969 is about 278.9842833179.

The spelling of 21713969 in words is "twenty-one million, seven hundred thirteen thousand, nine hundred sixty-nine".