21286993 has 8 divisors (see below), whose sum is σ = 26199488. Its totient is φ = 16842384.

The previous prime is 21286981. The next prime is 21286999. The reversal of 21286993 is 39968212.

It is a happy number.

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

It is not a de Polignac number, because 21286993 - 2⁵ = 21286961 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21286999) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 116871 + ... + 117052.

It is an arithmetic number, because the mean of its divisors is an integer number (3274936).

Almost surely, 2^21286993 is an apocalyptic number.

It is an amenable number.

21286993 is a deficient number, since it is larger than the sum of its proper divisors (4912495).

21286993 is a wasteful number, since it uses less digits than its factorization.

21286993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 233943.

The product of its digits is 46656, while the sum is 40.

The square root of 21286993 is about 4613.7829381105. The cubic root of 21286993 is about 277.1435479564.

The spelling of 21286993 in words is "twenty-one million, two hundred eighty-six thousand, nine hundred ninety-three".