21851460 has 144 divisors (see below), whose sum is σ = 72452016. Its totient is φ = 5308416.

The previous prime is 21851441. The next prime is 21851461. The reversal of 21851460 is 6415812.

It can be written as a sum of positive squares in 8 ways, for example, as 617796 + 21233664 = 786^2 + 4608^2 .

It is not an unprimeable number, because it can be changed into a prime (21851461) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 113124 + ... + 113316.

It is an arithmetic number, because the mean of its divisors is an integer number (503139).

Almost surely, 2^21851460 is an apocalyptic number.

21851460 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 21851460, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36226008).

21851460 is an abundant number, since it is smaller than the sum of its proper divisors (50600556).

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

21851460 is a wasteful number, since it uses less digits than its factorization.

21851460 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262 (or 257 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 21851460 is about 4674.5545242301. The cubic root of 21851460 is about 279.5718797510.

The spelling of 21851460 in words is "twenty-one million, eight hundred fifty-one thousand, four hundred sixty".