1251640291 has 8 divisors (see below), whose sum is σ = 1367229168. Its totient is φ = 1136352000.

The previous prime is 1251640279. The next prime is 1251640297. The reversal of 1251640291 is 1920461521.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1251640291 - 2⁷ = 1251640163 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1251640297) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 66390 + ... + 83131.

It is an arithmetic number, because the mean of its divisors is an integer number (170903646).

Almost surely, 2^1251640291 is an apocalyptic number.

1251640291 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1251640291 is a deficient number, since it is larger than the sum of its proper divisors (115588877).

1251640291 is a wasteful number, since it uses less digits than its factorization.

1251640291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 150293.

The product of its (nonzero) digits is 4320, while the sum is 31.

The square root of 1251640291 is about 35378.5286720632. The cubic root of 1251640291 is about 1077.6883257082.

The spelling of 1251640291 in words is "one billion, two hundred fifty-one million, six hundred forty thousand, two hundred ninety-one".