21898918 has 4 divisors (see below), whose sum is σ = 32848380. Its totient is φ = 10949458.

The previous prime is 21898913. The next prime is 21898937. The reversal of 21898918 is 81989812.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21898913) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5474728 + ... + 5474731.

It is an arithmetic number, because the mean of its divisors is an integer number (8212095).

Almost surely, 2^21898918 is an apocalyptic number.

21898918 is a deficient number, since it is larger than the sum of its proper divisors (10949462).

21898918 is a wasteful number, since it uses less digits than its factorization.

21898918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10949461.

The product of its digits is 82944, while the sum is 46.

The square root of 21898918 is about 4679.6279766665. The cubic root of 21898918 is about 279.7741290675.

The spelling of 21898918 in words is "twenty-one million, eight hundred ninety-eight thousand, nine hundred eighteen".