21023998 has 8 divisors (see below), whose sum is σ = 31718808. Its totient is φ = 10451064.

The previous prime is 21023971. The next prime is 21024067. The reversal of 21023998 is 89932012.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30036 + ... + 30727.

It is an arithmetic number, because the mean of its divisors is an integer number (3964851).

Almost surely, 2^21023998 is an apocalyptic number.

21023998 is a deficient number, since it is larger than the sum of its proper divisors (10694810).

21023998 is a wasteful number, since it uses less digits than its factorization.

21023998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60938.

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 21023998 is about 4585.1933437970. The cubic root of 21023998 is about 275.9974707463.

The spelling of 21023998 in words is "twenty-one million, twenty-three thousand, nine hundred ninety-eight".