21998012 has 12 divisors (see below), whose sum is σ = 38613120. Its totient is φ = 10965696.

The previous prime is 21997981. The next prime is 21998027. The reversal of 21998012 is 21089912.

It is a happy number.

It is a super-5 number, since 5×21998012⁵ (a number of 38 digits) contains 55555 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21998012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6812 + ... + 9507.

It is an arithmetic number, because the mean of its divisors is an integer number (3217760).

Almost surely, 2^21998012 is an apocalyptic number.

It is an amenable number.

21998012 is a deficient number, since it is larger than the sum of its proper divisors (16615108).

21998012 is a wasteful number, since it uses less digits than its factorization.

21998012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16660 (or 16658 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 21998012 is about 4690.2038335237. The cubic root of 21998012 is about 280.1954927292.

The spelling of 21998012 in words is "twenty-one million, nine hundred ninety-eight thousand, twelve".