21998064 has 80 divisors (see below), whose sum is σ = 63103104. Its totient is φ = 6547200.

The previous prime is 21998033. The next prime is 21998107. The reversal of 21998064 is 46089912.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31867 + ... + 32549.

Almost surely, 2^21998064 is an apocalyptic number.

21998064 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21998064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31551552).

21998064 is an abundant number, since it is smaller than the sum of its proper divisors (41105040).

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

21998064 is a wasteful number, since it uses less digits than its factorization.

21998064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 766 (or 760 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 39.

The square root of 21998064 is about 4690.2093769895. The cubic root of 21998064 is about 280.1957135091.

The spelling of 21998064 in words is "twenty-one million, nine hundred ninety-eight thousand, sixty-four".