21023986 has 8 divisors (see below), whose sum is σ = 31556844. Its totient is φ = 10505040.

The previous prime is 21023971. The next prime is 21024067. The reversal of 21023986 is 68932012.

It can be written as a sum of positive squares in 2 ways, for example, as 20875761 + 148225 = 4569^2 + 385^2 .

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

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 2076 + ... + 6808.

Almost surely, 2^21023986 is an apocalyptic number.

21023986 is a deficient number, since it is larger than the sum of its proper divisors (10532858).

21023986 is a wasteful number, since it uses less digits than its factorization.

21023986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6956.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 21023986 is about 4585.1920352369. The cubic root of 21023986 is about 275.9974182353.

Adding to 21023986 its reverse (68932012), we get a palindrome (89955998).

The spelling of 21023986 in words is "twenty-one million, twenty-three thousand, nine hundred eighty-six".