21964220 has 12 divisors (see below), whose sum is σ = 46124904. Its totient is φ = 8785680.

The previous prime is 21964219. The next prime is 21964231. The reversal of 21964220 is 2246912.

It is a self number, because there is not a number n which added to its sum of digits gives 21964220.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 549086 + ... + 549125.

It is an arithmetic number, because the mean of its divisors is an integer number (3843742).

Almost surely, 2^21964220 is an apocalyptic number.

21964220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21964220 is an abundant number, since it is smaller than the sum of its proper divisors (24160684).

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

21964220 is a wasteful number, since it uses less digits than its factorization.

21964220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1098220 (or 1098218 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 21964220 is about 4686.6000469423. The cubic root of 21964220 is about 280.0519461446.

The spelling of 21964220 in words is "twenty-one million, nine hundred sixty-four thousand, two hundred twenty".