25640720 has 120 divisors (see below), whose sum is σ = 71923968. Its totient is φ = 8467200.

The previous prime is 25640683. The next prime is 25640729. The reversal of 25640720 is 2704652.

It is a self number, because there is not a number n which added to its sum of digits gives 25640720.

It is not an unprimeable number, because it can be changed into a prime (25640729) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 121415 + ... + 121625.

Almost surely, 2^25640720 is an apocalyptic number.

25640720 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 25640720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35961984).

25640720 is an abundant number, since it is smaller than the sum of its proper divisors (46283248).

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

25640720 is a wasteful number, since it uses less digits than its factorization.

25640720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 269 (or 256 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 26.

The square root of 25640720 is about 5063.6666556953. Note that the first 4 decimals coincide. The cubic root of 25640720 is about 294.8787014478.

The spelling of 25640720 in words is "twenty-five million, six hundred forty thousand, seven hundred twenty".