991749089956 has 81 divisors (see below), whose sum is σ = 1862337091041. Its totient is φ = 462049956288.

The previous prime is 991749089873. The next prime is 991749090023. The reversal of 991749089956 is 659980947199.

The square root of 991749089956 is 995866.

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

991749089956 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 562965096100 + 428783993856 = 750310^2 + 654816^2 .

It is a Harshad number since it is a multiple of its sum of digits (76).

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 2762532105 + ... + 2762532463.

Almost surely, 2^991749089956 is an apocalyptic number.

991749089956 is the 995866-th square number.

It is an amenable number.

991749089956 is a deficient number, since it is larger than the sum of its proper divisors (870588001085).

991749089956 is an equidigital number, since it uses as much as digits as its factorization.

991749089956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 906 (or 453 counting only the distinct ones).

The product of its (nonzero) digits is 396809280, while the sum is 76.

It can be divided in two parts, 991 and 749089956, that added together give a palindrome (749090947).

The spelling of 991749089956 in words is "nine hundred ninety-one billion, seven hundred forty-nine million, eighty-nine thousand, nine hundred fifty-six".