21890620 has 12 divisors (see below), whose sum is σ = 45970344. Its totient is φ = 8756240.

The previous prime is 21890599. The next prime is 21890623. The reversal of 21890620 is 2609812.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21890623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 547246 + ... + 547285.

It is an arithmetic number, because the mean of its divisors is an integer number (3830862).

Almost surely, 2^21890620 is an apocalyptic number.

21890620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21890620 is an abundant number, since it is smaller than the sum of its proper divisors (24079724).

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

21890620 is a wasteful number, since it uses less digits than its factorization.

21890620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1094540 (or 1094538 counting only the distinct ones).

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

The square root of 21890620 is about 4678.7412837215. The cubic root of 21890620 is about 279.7387870015.

The spelling of 21890620 in words is "twenty-one million, eight hundred ninety thousand, six hundred twenty".