21898728 has 32 divisors (see below), whose sum is σ = 60830400. Its totient is φ = 7299504.

The previous prime is 21898711. The next prime is 21898729. The reversal of 21898728 is 82789812.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21898729) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 50476 + ... + 50907.

It is an arithmetic number, because the mean of its divisors is an integer number (1900950).

Almost surely, 2^21898728 is an apocalyptic number.

It is an amenable number.

21898728 is an abundant number, since it is smaller than the sum of its proper divisors (38931672).

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

21898728 is a wasteful number, since it uses less digits than its factorization.

21898728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101398 (or 101388 counting only the distinct ones).

The product of its digits is 129024, while the sum is 45.

The square root of 21898728 is about 4679.6076758634. The cubic root of 21898728 is about 279.7733199371.

The spelling of 21898728 in words is "twenty-one million, eight hundred ninety-eight thousand, seven hundred twenty-eight".