21253960 has 64 divisors (see below), whose sum is σ = 58867200. Its totient is φ = 6725376.

The previous prime is 21253957. The next prime is 21253963. The reversal of 21253960 is 6935212.

It is an interprime number because it is at equal distance from previous prime (21253957) and next prime (21253963).

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253963) 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, 721 + ... + 6559.

It is an arithmetic number, because the mean of its divisors is an integer number (919800).

Almost surely, 2^21253960 is an apocalyptic number.

21253960 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 21253960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29433600).

21253960 is an abundant number, since it is smaller than the sum of its proper divisors (37613240).

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

21253960 is a wasteful number, since it uses less digits than its factorization.

21253960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5870 (or 5866 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 28.

The square root of 21253960 is about 4610.2017309441. The cubic root of 21253960 is about 277.0001172959. Note that the first 3 decimals are identical.

The spelling of 21253960 in words is "twenty-one million, two hundred fifty-three thousand, nine hundred sixty".