21213992 has 16 divisors (see below), whose sum is σ = 40527540. Its totient is φ = 10406656.

The previous prime is 21213991. The next prime is 21214001. The reversal of 21213992 is 29931212.

It can be written as a sum of positive squares in 2 ways, for example, as 20484676 + 729316 = 4526^2 + 854^2 .

It is not an unprimeable number, because it can be changed into a prime (21213991) 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 3 ways as a sum of consecutive naturals, for example, 24593 + ... + 25440.

Almost surely, 2^21213992 is an apocalyptic number.

It is an amenable number.

21213992 is a deficient number, since it is larger than the sum of its proper divisors (19313548).

21213992 is a wasteful number, since it uses less digits than its factorization.

21213992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50092 (or 50088 counting only the distinct ones).

The product of its digits is 1944, while the sum is 29.

The square root of 21213992 is about 4605.8649567698. The cubic root of 21213992 is about 276.8263757485.

The spelling of 21213992 in words is "twenty-one million, two hundred thirteen thousand, nine hundred ninety-two".