991087540 has 48 divisors (see below), whose sum is σ = 2100639744. Its totient is φ = 392768000.

The previous prime is 991087529. The next prime is 991087541. The reversal of 991087540 is 45780199.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991087541) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1531497 + ... + 1532143.

It is an arithmetic number, because the mean of its divisors is an integer number (43763328).

Almost surely, 2^991087540 is an apocalyptic number.

It is an amenable number.

991087540 is an abundant number, since it is smaller than the sum of its proper divisors (1109552204).

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

991087540 is a wasteful number, since it uses less digits than its factorization.

991087540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1248 (or 1246 counting only the distinct ones).

The product of its (nonzero) digits is 90720, while the sum is 43.

The square root of 991087540 is about 31481.5428465633. The cubic root of 991087540 is about 997.0203102675.

The spelling of 991087540 in words is "nine hundred ninety-one million, eighty-seven thousand, five hundred forty".