21089860 has 48 divisors (see below), whose sum is σ = 51166080. Its totient is φ = 7216640.

The previous prime is 21089857. The next prime is 21089863. The reversal of 21089860 is 6898012.

21089860 = T₁₃₁ + T₁₃₂ + ... + T₅₀₄.

It is an interprime number because it is at equal distance from previous prime (21089857) and next prime (21089863).

It is a Harshad number since it is a multiple of its sum of digits (34).

It is not an unprimeable number, because it can be changed into a prime (21089863) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 921 + ... + 6559.

It is an arithmetic number, because the mean of its divisors is an integer number (1065960).

Almost surely, 2^21089860 is an apocalyptic number.

21089860 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 21089860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25583040).

21089860 is an abundant number, since it is smaller than the sum of its proper divisors (30076220).

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

21089860 is a wasteful number, since it uses less digits than its factorization.

21089860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5676 (or 5674 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 34.

The square root of 21089860 is about 4592.3697586322. The cubic root of 21089860 is about 276.2853766042.

The spelling of 21089860 in words is "twenty-one million, eighty-nine thousand, eight hundred sixty".