991407897825 has 24 divisors (see below), whose sum is σ = 1639226928000. Its totient is φ = 528718877760.

The previous prime is 991407897793. The next prime is 991407897839. The reversal of 991407897825 is 528798704199.

It is not a de Polignac number, because 991407897825 - 2⁵ = 991407897793 is a prime.

It is a super-3 number, since 3×991407897825³ (a number of 37 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 991407897825.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 874351 + ... + 1657499.

It is an arithmetic number, because the mean of its divisors is an integer number (68301122000).

Almost surely, 2^991407897825 is an apocalyptic number.

It is an amenable number.

991407897825 is a deficient number, since it is larger than the sum of its proper divisors (647819030175).

991407897825 is a wasteful number, since it uses less digits than its factorization.

991407897825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 800041 (or 800036 counting only the distinct ones).

The product of its (nonzero) digits is 91445760, while the sum is 69.

The spelling of 991407897825 in words is "nine hundred ninety-one billion, four hundred seven million, eight hundred ninety-seven thousand, eight hundred twenty-five".