991581791524 has 27 divisors (see below), whose sum is σ = 1793161863633. Its totient is φ = 479767767600.

The previous prime is 991581791507. The next prime is 991581791531. The reversal of 991581791524 is 425197185199.

The square root of 991581791524 is 995782.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 9976413924 + 981605377600 = 99882^2 + 990760^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 61730454 + ... + 61746514.

Almost surely, 2^991581791524 is an apocalyptic number.

991581791524 is the 995782-nd square number.

It is an amenable number.

991581791524 is a deficient number, since it is larger than the sum of its proper divisors (801580072109).

991581791524 is an frugal number, since it uses more digits than its factorization.

991581791524 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32188 (or 16094 counting only the distinct ones).

The product of its digits is 8164800, while the sum is 61.

The spelling of 991581791524 in words is "nine hundred ninety-one billion, five hundred eighty-one million, seven hundred ninety-one thousand, five hundred twenty-four".