21865966 has 8 divisors (see below), whose sum is σ = 32882760. Its totient is φ = 10905048.

The previous prime is 21865957. The next prime is 21865967. The reversal of 21865966 is 66956812.

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

It is a super-2 number, since 2×21865966² = 956240938226312, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21865967) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12976 + ... + 14563.

It is an arithmetic number, because the mean of its divisors is an integer number (4110345).

Almost surely, 2^21865966 is an apocalyptic number.

21865966 is a deficient number, since it is larger than the sum of its proper divisors (11016794).

21865966 is a wasteful number, since it uses less digits than its factorization.

21865966 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27938.

The product of its digits is 155520, while the sum is 43.

The square root of 21865966 is about 4676.1058585109. The cubic root of 21865966 is about 279.6337302729.

The spelling of 21865966 in words is "twenty-one million, eight hundred sixty-five thousand, nine hundred sixty-six".