749991561 has 16 divisors (see below), whose sum is σ = 1105844160. Its totient is φ = 448312320.

The previous prime is 749991553. The next prime is 749991581. The reversal of 749991561 is 165199947.

It is not a de Polignac number, because 749991561 - 2³ = 749991553 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (749991581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 153256 + ... + 158073.

It is an arithmetic number, because the mean of its divisors is an integer number (69115260).

Almost surely, 2^749991561 is an apocalyptic number.

It is an amenable number.

749991561 is a deficient number, since it is larger than the sum of its proper divisors (355852599).

749991561 is a wasteful number, since it uses less digits than its factorization.

749991561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 311416.

The product of its digits is 612360, while the sum is 51.

The square root of 749991561 is about 27385.9738004695. The cubic root of 749991561 is about 908.5568886965.

The spelling of 749991561 in words is "seven hundred forty-nine million, nine hundred ninety-one thousand, five hundred sixty-one".