21493920 has 96 divisors (see below), whose sum is σ = 77390208. Its totient is φ = 4912128.

The previous prime is 21493909. The next prime is 21493951. The reversal of 21493920 is 2939412.

It is a tau number, because it is divible by the number of its divisors (96).

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

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, 162 + ... + 6558.

It is an arithmetic number, because the mean of its divisors is an integer number (806148).

Almost surely, 2^21493920 is an apocalyptic number.

21493920 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 21493920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38695104).

21493920 is an abundant number, since it is smaller than the sum of its proper divisors (55896288).

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

21493920 is a wasteful number, since it uses less digits than its factorization.

21493920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6422 (or 6414 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 30.

The square root of 21493920 is about 4636.1535781292. The cubic root of 21493920 is about 278.0386744670.

The spelling of 21493920 in words is "twenty-one million, four hundred ninety-three thousand, nine hundred twenty".