25221720 has 64 divisors (see below), whose sum is σ = 76451040. Its totient is φ = 6656000.

The previous prime is 25221673. The next prime is 25221739. The reversal of 25221720 is 2712252.

It is a happy number.

It is a super-2 number, since 2×25221720² = 1272270319516800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11080 + ... + 13160.

Almost surely, 2^25221720 is an apocalyptic number.

25221720 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 25221720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38225520).

25221720 is an abundant number, since it is smaller than the sum of its proper divisors (51229320).

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

25221720 is a wasteful number, since it uses less digits than its factorization.

25221720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2196 (or 2192 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 25221720 is about 5022.1230570347. The cubic root of 25221720 is about 293.2636485065.

Adding to 25221720 its reverse (2712252), we get a palindrome (27933972).

The spelling of 25221720 in words is "twenty-five million, two hundred twenty-one thousand, seven hundred twenty".