21698020 has 48 divisors (see below), whose sum is σ = 47755008. Its totient is φ = 8272640.

The previous prime is 21697997. The next prime is 21698029. The reversal of 21698020 is 2089612.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21698020.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21698029) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38259 + ... + 38821.

It is an arithmetic number, because the mean of its divisors is an integer number (994896).

Almost surely, 2^21698020 is an apocalyptic number.

21698020 is a gapful number since it is divisible by the number (20) 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 21698020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23877504).

21698020 is an abundant number, since it is smaller than the sum of its proper divisors (26056988).

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

21698020 is a wasteful number, since it uses less digits than its factorization.

21698020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 660 (or 658 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 21698020 is about 4658.1133519913. The cubic root of 21698020 is about 278.9159615512.

The spelling of 21698020 in words is "twenty-one million, six hundred ninety-eight thousand, twenty".