25781199642 has 64 divisors (see below), whose sum is σ = 62573875200. Its totient is φ = 7803235440.

The previous prime is 25781199589. The next prime is 25781199649. The reversal of 25781199642 is 24699118752.

It is a happy number.

25781199642 is a `hidden beast` number, since 2 + 578 + 1 + 1 + 9 + 9 + 64 + 2 = 666.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (25781199649) 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, 484983 + ... + 535509.

It is an arithmetic number, because the mean of its divisors is an integer number (977716800).

Almost surely, 2^25781199642 is an apocalyptic number.

25781199642 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 25781199642, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31286937600).

25781199642 is an abundant number, since it is smaller than the sum of its proper divisors (36792675558).

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

25781199642 is a wasteful number, since it uses less digits than its factorization.

25781199642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51408 (or 51402 counting only the distinct ones).

The product of its digits is 2177280, while the sum is 54.

The spelling of 25781199642 in words is "twenty-five billion, seven hundred eighty-one million, one hundred ninety-nine thousand, six hundred forty-two".