21998718 has 48 divisors (see below), whose sum is σ = 56848896. Its totient is φ = 6011280.

The previous prime is 21998701. The next prime is 21998723. The reversal of 21998718 is 81789912.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 898 + ... + 6693.

It is an arithmetic number, because the mean of its divisors is an integer number (1184352).

Almost surely, 2^21998718 is an apocalyptic number.

21998718 is an abundant number, since it is smaller than the sum of its proper divisors (34850178).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21998718 is a wasteful number, since it uses less digits than its factorization.

21998718 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7629 (or 7626 counting only the distinct ones).

The product of its digits is 72576, while the sum is 45.

The square root of 21998718 is about 4690.2790961733. The cubic root of 21998718 is about 280.1984902107.

The spelling of 21998718 in words is "twenty-one million, nine hundred ninety-eight thousand, seven hundred eighteen".