21986220 has 24 divisors (see below), whose sum is σ = 61561584. Its totient is φ = 5862976.

The previous prime is 21986203. The next prime is 21986221. The reversal of 21986220 is 2268912.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (21986221) 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, 183159 + ... + 183278.

It is an arithmetic number, because the mean of its divisors is an integer number (2565066).

Almost surely, 2^21986220 is an apocalyptic number.

21986220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21986220 is an abundant number, since it is smaller than the sum of its proper divisors (39575364).

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

21986220 is a wasteful number, since it uses less digits than its factorization.

21986220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 366449 (or 366447 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 21986220 is about 4688.9465767910. The cubic root of 21986220 is about 280.1454176617.

The spelling of 21986220 in words is "twenty-one million, nine hundred eighty-six thousand, two hundred twenty".