21336810 has 128 divisors (see below), whose sum is σ = 60963840. Its totient is φ = 4723200.

The previous prime is 21336803. The next prime is 21336839. The reversal of 21336810 is 1863312.

It is a super-2 number, since 2×21336810² = 910518921952200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 257029 + ... + 257111.

It is an arithmetic number, because the mean of its divisors is an integer number (476280).

Almost surely, 2^21336810 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21336810, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30481920).

21336810 is an abundant number, since it is smaller than the sum of its proper divisors (39627030).

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

21336810 is a wasteful number, since it uses less digits than its factorization.

21336810 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 21336810 is about 4619.1784983912. The cubic root of 21336810 is about 277.3595750846.

The spelling of 21336810 in words is "twenty-one million, three hundred thirty-six thousand, eight hundred ten".