25991820 has 96 divisors (see below), whose sum is σ = 81715200. Its totient is φ = 6858432.

The previous prime is 25991809. The next prime is 25991831. The reversal of 25991820 is 2819952.

It is an interprime number because it is at equal distance from previous prime (25991809) and next prime (25991831).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 68391 + ... + 68769.

It is an arithmetic number, because the mean of its divisors is an integer number (851200).

Almost surely, 2^25991820 is an apocalyptic number.

25991820 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 25991820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40857600).

25991820 is an abundant number, since it is smaller than the sum of its proper divisors (55723380).

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

25991820 is a wasteful number, since it uses less digits than its factorization.

25991820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 524 (or 516 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 25991820 is about 5098.2173355007. The cubic root of 25991820 is about 296.2185353540.

The spelling of 25991820 in words is "twenty-five million, nine hundred ninety-one thousand, eight hundred twenty".