21457580 has 48 divisors (see below), whose sum is σ = 47464704. Its totient is φ = 8136960.

The previous prime is 21457523. The next prime is 21457603. The reversal of 21457580 is 8575412.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32534 + ... + 33186.

It is an arithmetic number, because the mean of its divisors is an integer number (988848).

Almost surely, 2^21457580 is an apocalyptic number.

21457580 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 21457580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23732352).

21457580 is an abundant number, since it is smaller than the sum of its proper divisors (26007124).

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

21457580 is a wasteful number, since it uses less digits than its factorization.

21457580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 746 (or 744 counting only the distinct ones).

The product of its (nonzero) digits is 11200, while the sum is 32.

The square root of 21457580 is about 4632.2327229965. The cubic root of 21457580 is about 277.8818917573.

The spelling of 21457580 in words is "twenty-one million, four hundred fifty-seven thousand, five hundred eighty".