21980398 has 16 divisors (see below), whose sum is σ = 36255744. Its totient is φ = 9911160.

The previous prime is 21980389. The next prime is 21980401. The reversal of 21980398 is 89308912.

It is a self number, because there is not a number n which added to its sum of digits gives 21980398.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1140 + ... + 6727.

It is an arithmetic number, because the mean of its divisors is an integer number (2265984).

Almost surely, 2^21980398 is an apocalyptic number.

21980398 is a deficient number, since it is larger than the sum of its proper divisors (14275346).

21980398 is a wasteful number, since it uses less digits than its factorization.

21980398 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8007.

The product of its (nonzero) digits is 31104, while the sum is 40.

The square root of 21980398 is about 4688.3257139410. The cubic root of 21980398 is about 280.1206877687.

The spelling of 21980398 in words is "twenty-one million, nine hundred eighty thousand, three hundred ninety-eight".