25810671649 has 27 divisors (see below), whose sum is σ = 30620893107. Its totient is φ = 21692550768.

The previous prime is 25810671589. The next prime is 25810671659. The reversal of 25810671649 is 94617601852.

It is a happy number.

The square root of 25810671649 is 160657.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 6092895249 + 19717776400 = 78057^2 + 140420^2 .

It is not a de Polignac number, because 25810671649 - 2⁷ = 25810671521 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is not an unprimeable number, because it can be changed into a prime (25810671659) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 66351147 + ... + 66351535.

Almost surely, 2^25810671649 is an apocalyptic number.

25810671649 is the 160657-th square number.

25810671649 is the 80329-th centered octagonal number.

It is an amenable number.

25810671649 is a deficient number, since it is larger than the sum of its proper divisors (4810221458).

25810671649 is an frugal number, since it uses more digits than its factorization.

25810671649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 910 (or 455 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 49.

Multiplying 25810671649 by its sum of digits (49), we get a square (1264722910801 = 1124599²).

25810671649 divided by its sum of digits (49) gives a square (526748401 = 22951²).

The spelling of 25810671649 in words is "twenty-five billion, eight hundred ten million, six hundred seventy-one thousand, six hundred forty-nine".