25251661 has 2 divisors, whose sum is σ = 25251662. Its totient is φ = 25251660.

The previous prime is 25251623. The next prime is 25251673. The reversal of 25251661 is 16615252.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20385225 + 4866436 = 4515^2 + 2206^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25251661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25251761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12625830 + 12625831.

It is an arithmetic number, because the mean of its divisors is an integer number (12625831).

Almost surely, 2^25251661 is an apocalyptic number.

It is an amenable number.

25251661 is a deficient number, since it is larger than the sum of its proper divisors (1).

25251661 is an equidigital number, since it uses as much as digits as its factorization.

25251661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3600, while the sum is 28.

The square root of 25251661 is about 5025.1030835198. The cubic root of 25251661 is about 293.3796481908.

It can be divided in two parts, 2525 and 1661, that added together give a triangular number (4186 = T₉₁).

The spelling of 25251661 in words is "twenty-five million, two hundred fifty-one thousand, six hundred sixty-one".