21445620 has 48 divisors (see below), whose sum is σ = 68627328. Its totient is φ = 4901760.

The previous prime is 21445609. The next prime is 21445643. The reversal of 21445620 is 2654412.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25111 + ... + 25950.

It is an arithmetic number, because the mean of its divisors is an integer number (1429736).

Almost surely, 2^21445620 is an apocalyptic number.

21445620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21445620 is an abundant number, since it is smaller than the sum of its proper divisors (47181708).

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

21445620 is a wasteful number, since it uses less digits than its factorization.

21445620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51080 (or 51078 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 24.

The square root of 21445620 is about 4630.9415889212. The cubic root of 21445620 is about 277.8302536712.

The spelling of 21445620 in words is "twenty-one million, four hundred forty-five thousand, six hundred twenty".