25661223979 has 2 divisors, whose sum is σ = 25661223980. Its totient is φ = 25661223978.

The previous prime is 25661223967. The next prime is 25661224049. The reversal of 25661223979 is 97932216652.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 25661223979 - 2²³ = 25652835371 is a prime.

It is a super-2 number, since 2×25661223979² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (25661223079) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12830611989 + 12830611990.

It is an arithmetic number, because the mean of its divisors is an integer number (12830611990).

Almost surely, 2^25661223979 is an apocalyptic number.

25661223979 is a deficient number, since it is larger than the sum of its proper divisors (1).

25661223979 is an equidigital number, since it uses as much as digits as its factorization.

25661223979 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2449440, while the sum is 52.

The spelling of 25661223979 in words is "twenty-five billion, six hundred sixty-one million, two hundred twenty-three thousand, nine hundred seventy-nine".