21098664 has 128 divisors (see below), whose sum is σ = 63504000. Its totient is φ = 6469632.

The previous prime is 21098663. The next prime is 21098669. The reversal of 21098664 is 46689012.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21098663) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 217464 + ... + 217560.

It is an arithmetic number, because the mean of its divisors is an integer number (496125).

Almost surely, 2^21098664 is an apocalyptic number.

21098664 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 21098664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31752000).

21098664 is an abundant number, since it is smaller than the sum of its proper divisors (42405336).

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

21098664 is a wasteful number, since it uses less digits than its factorization.

21098664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 184 (or 174 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 21098664 is about 4593.3282051253. The cubic root of 21098664 is about 276.3238165316.

The spelling of 21098664 in words is "twenty-one million, ninety-eight thousand, six hundred sixty-four".