825709991 has 4 divisors (see below), whose sum is σ = 827070912. Its totient is φ = 824349072.

The previous prime is 825709981. The next prime is 825709993. The reversal of 825709991 is 199907528.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 825709991 - 2²⁶ = 758601127 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (825709993) 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 3 ways as a sum of consecutive naturals, for example, 679550 + ... + 680763.

It is an arithmetic number, because the mean of its divisors is an integer number (206767728).

Almost surely, 2^825709991 is an apocalyptic number.

825709991 is a deficient number, since it is larger than the sum of its proper divisors (1360921).

825709991 is a wasteful number, since it uses less digits than its factorization.

825709991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1360920.

The product of its (nonzero) digits is 408240, while the sum is 50.

The square root of 825709991 is about 28735.1699316360. The cubic root of 825709991 is about 938.1576980372.

The spelling of 825709991 in words is "eight hundred twenty-five million, seven hundred nine thousand, nine hundred ninety-one".