21726380 has 24 divisors (see below), whose sum is σ = 49135632. Its totient is φ = 8021952.

The previous prime is 21726379. The next prime is 21726389. The reversal of 21726380 is 8362712.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21726389) 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 7 ways as a sum of consecutive naturals, for example, 41522 + ... + 42041.

It is an arithmetic number, because the mean of its divisors is an integer number (2047318).

Almost surely, 2^21726380 is an apocalyptic number.

21726380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21726380 is an abundant number, since it is smaller than the sum of its proper divisors (27409252).

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

21726380 is a wasteful number, since it uses less digits than its factorization.

21726380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83585 (or 83583 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 21726380 is about 4661.1565088506. The cubic root of 21726380 is about 279.0374259818.

The spelling of 21726380 in words is "twenty-one million, seven hundred twenty-six thousand, three hundred eighty".