1253921665 has 4 divisors (see below), whose sum is σ = 1504706004. Its totient is φ = 1003137328.

The previous prime is 1253921653. The next prime is 1253921677. The reversal of 1253921665 is 5661293521.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (1253921653) and next prime (1253921677).

It can be written as a sum of positive squares in 2 ways, for example, as 725979136 + 527942529 = 26944^2 + 22977^2 .

It is a cyclic number.

It is not a de Polignac number, because 1253921665 - 2²⁵ = 1220367233 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 125392162 + ... + 125392171.

It is an arithmetic number, because the mean of its divisors is an integer number (376176501).

Almost surely, 2^1253921665 is an apocalyptic number.

It is an amenable number.

1253921665 is a deficient number, since it is larger than the sum of its proper divisors (250784339).

1253921665 is an equidigital number, since it uses as much as digits as its factorization.

1253921665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 250784338.

The product of its digits is 97200, while the sum is 40.

The square root of 1253921665 is about 35410.7563460596. The cubic root of 1253921665 is about 1078.3426984485.

The spelling of 1253921665 in words is "one billion, two hundred fifty-three million, nine hundred twenty-one thousand, six hundred sixty-five".