21358890 has 80 divisors (see below), whose sum is σ = 65653632. Its totient is φ = 4880736.

The previous prime is 21358873. The next prime is 21358901. The reversal of 21358890 is 9885312.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 3787 + ... + 7553.

Almost surely, 2^21358890 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21358890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32826816).

21358890 is an abundant number, since it is smaller than the sum of its proper divisors (44294742).

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

21358890 is a wasteful number, since it uses less digits than its factorization.

21358890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3793 (or 3784 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 21358890 is about 4621.5679157619. The cubic root of 21358890 is about 277.4552155632.

It can be divided in two parts, 2135 and 8890, that added together give a square (11025 = 105²).

The spelling of 21358890 in words is "twenty-one million, three hundred fifty-eight thousand, eight hundred ninety".