21299580 has 72 divisors (see below), whose sum is σ = 65008944. Its totient is φ = 5644800.

The previous prime is 21299561. The next prime is 21299591. The reversal of 21299580 is 8599212.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 43135 + ... + 43625.

It is an arithmetic number, because the mean of its divisors is an integer number (902902).

Almost surely, 2^21299580 is an apocalyptic number.

21299580 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 21299580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32504472).

21299580 is an abundant number, since it is smaller than the sum of its proper divisors (43709364).

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

21299580 is a wasteful number, since it uses less digits than its factorization.

21299580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 747 (or 742 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 21299580 is about 4615.1468015655. The cubic root of 21299580 is about 277.1981621912.

The spelling of 21299580 in words is "twenty-one million, two hundred ninety-nine thousand, five hundred eighty".