25643540 has 96 divisors (see below), whose sum is σ = 63504000. Its totient is φ = 8612352.

The previous prime is 25643539. The next prime is 25643543. The reversal of 25643540 is 4534652.

It is a super-2 number, since 2×25643540² = 1315182287463200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25643543) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 143171 + ... + 143349.

It is an arithmetic number, because the mean of its divisors is an integer number (661500).

Almost surely, 2^25643540 is an apocalyptic number.

25643540 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 25643540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31752000).

25643540 is an abundant number, since it is smaller than the sum of its proper divisors (37860460).

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

25643540 is a wasteful number, since it uses less digits than its factorization.

25643540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249 (or 247 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 29.

The square root of 25643540 is about 5063.9451023881. The cubic root of 25643540 is about 294.8895114335.

The spelling of 25643540 in words is "twenty-five million, six hundred forty-three thousand, five hundred forty".