15661651025 has 12 divisors (see below), whose sum is σ = 19448902512. Its totient is φ = 12510962640.

The previous prime is 15661651001. The next prime is 15661651091. The reversal of 15661651025 is 52015616651.

It is a happy number.

It is not a de Polignac number, because 15661651025 - 2¹⁰ = 15661650001 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 15661651025.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 441539 + ... + 475688.

It is an arithmetic number, because the mean of its divisors is an integer number (1620741876).

Almost surely, 2^15661651025 is an apocalyptic number.

It is an amenable number.

15661651025 is a deficient number, since it is larger than the sum of its proper divisors (3787251487).

15661651025 is an equidigital number, since it uses as much as digits as its factorization.

15661651025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 917920 (or 917915 counting only the distinct ones).

The product of its (nonzero) digits is 54000, while the sum is 38.

The spelling of 15661651025 in words is "fifteen billion, six hundred sixty-one million, six hundred fifty-one thousand, twenty-five".