991225089880 has 32 divisors (see below), whose sum is σ = 2240257622400. Its totient is φ = 394712050176.

The previous prime is 991225089853. The next prime is 991225089947. The reversal of 991225089880 is 88980522199.

It is a happy number.

It is a super-2 number, since 2×991225089880² (a number of 25 digits) contains 22 as substring.

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, 55553025 + ... + 55570864.

It is an arithmetic number, because the mean of its divisors is an integer number (70008050700).

Almost surely, 2^991225089880 is an apocalyptic number.

It is an amenable number.

991225089880 is an abundant number, since it is smaller than the sum of its proper divisors (1249032532520).

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

991225089880 is a wasteful number, since it uses less digits than its factorization.

991225089880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111124123 (or 111124119 counting only the distinct ones).

The product of its (nonzero) digits is 7464960, while the sum is 61.

The spelling of 991225089880 in words is "nine hundred ninety-one billion, two hundred twenty-five million, eighty-nine thousand, eight hundred eighty".