1991525717 has 8 divisors (see below), whose sum is σ = 2097782400. Its totient is φ = 1885413024.

The previous prime is 1991525699. The next prime is 1991525749. The reversal of 1991525717 is 7175251991.

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 1991525717 - 2⁸ = 1991525461 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991525317) 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, 6992 + ... + 63497.

It is an arithmetic number, because the mean of its divisors is an integer number (262222800).

Almost surely, 2^1991525717 is an apocalyptic number.

It is an amenable number.

1991525717 is a deficient number, since it is larger than the sum of its proper divisors (106256683).

1991525717 is a wasteful number, since it uses less digits than its factorization.

1991525717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71995.

The product of its digits is 198450, while the sum is 47.

The square root of 1991525717 is about 44626.5136101847. The cubic root of 1991525717 is about 1258.1390427254.

The spelling of 1991525717 in words is "one billion, nine hundred ninety-one million, five hundred twenty-five thousand, seven hundred seventeen".