1251025665 has 16 divisors (see below), whose sum is σ = 2119385088. Its totient is φ = 627965696.

The previous prime is 1251025651. The next prime is 1251025667. The reversal of 1251025665 is 5665201521.

It is a cyclic number.

It is not a de Polignac number, because 1251025665 - 2¹³ = 1251017473 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1251025667) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2452737 + ... + 2453246.

It is an arithmetic number, because the mean of its divisors is an integer number (132461568).

Almost surely, 2^1251025665 is an apocalyptic number.

1251025665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1251025665 is a deficient number, since it is larger than the sum of its proper divisors (868359423).

1251025665 is a wasteful number, since it uses less digits than its factorization.

1251025665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4906008.

The product of its (nonzero) digits is 18000, while the sum is 33.

The square root of 1251025665 is about 35369.8411786086. The cubic root of 1251025665 is about 1077.5118949023.

The spelling of 1251025665 in words is "one billion, two hundred fifty-one million, twenty-five thousand, six hundred sixty-five".