991240725820 has 24 divisors (see below), whose sum is σ = 2092503990528. Its totient is φ = 394420392000.

The previous prime is 991240725809. The next prime is 991240725877. The reversal of 991240725820 is 28527042199.

It is a happy number.

991240725820 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 129739731 + ... + 129747370.

It is an arithmetic number, because the mean of its divisors is an integer number (87187666272).

Almost surely, 2^991240725820 is an apocalyptic number.

It is an amenable number.

991240725820 is an abundant number, since it is smaller than the sum of its proper divisors (1101263264708).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991240725820 is a wasteful number, since it uses less digits than its factorization.

991240725820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 259487301 (or 259487299 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 49.

The spelling of 991240725820 in words is "nine hundred ninety-one billion, two hundred forty million, seven hundred twenty-five thousand, eight hundred twenty".