21389998 has 8 divisors (see below), whose sum is σ = 36668592. Its totient is φ = 9167136.

The previous prime is 21389971. The next prime is 21389999. The reversal of 21389998 is 89998312.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21389999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 763915 + ... + 763942.

It is an arithmetic number, because the mean of its divisors is an integer number (4583574).

Almost surely, 2^21389998 is an apocalyptic number.

21389998 is a deficient number, since it is larger than the sum of its proper divisors (15278594).

21389998 is a wasteful number, since it uses less digits than its factorization.

21389998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1527866.

The product of its digits is 279936, while the sum is 49.

The square root of 21389998 is about 4624.9322157195. The cubic root of 21389998 is about 277.5898494324.

The spelling of 21389998 in words is "twenty-one million, three hundred eighty-nine thousand, nine hundred ninety-eight".