21587020 has 96 divisors (see below), whose sum is σ = 57859200. Its totient is φ = 6580224.

The previous prime is 21587017. The next prime is 21587023. The reversal of 21587020 is 2078512.

It is an interprime number because it is at equal distance from previous prime (21587017) and next prime (21587023).

It is not an unprimeable number, because it can be changed into a prime (21587023) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 52576 + ... + 52984.

It is an arithmetic number, because the mean of its divisors is an integer number (602700).

Almost surely, 2^21587020 is an apocalyptic number.

21587020 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 21587020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28929600).

21587020 is an abundant number, since it is smaller than the sum of its proper divisors (36272180).

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

21587020 is a wasteful number, since it uses less digits than its factorization.

21587020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 467 (or 465 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 25.

The square root of 21587020 is about 4646.1833799367. The cubic root of 21587020 is about 278.4395338175.

The spelling of 21587020 in words is "twenty-one million, five hundred eighty-seven thousand, twenty".