991356641 has 8 divisors (see below), whose sum is σ = 1085304864. Its totient is φ = 898045920.

The previous prime is 991356491. The next prime is 991356643. The reversal of 991356641 is 146653199.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 991356641 - 2¹⁸ = 991094497 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 991356592 and 991356601.

It is not an unprimeable number, because it can be changed into a prime (991356643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 156116 + ... + 162341.

It is an arithmetic number, because the mean of its divisors is an integer number (135663108).

Almost surely, 2^991356641 is an apocalyptic number.

It is an amenable number.

991356641 is a deficient number, since it is larger than the sum of its proper divisors (93948223).

991356641 is a wasteful number, since it uses less digits than its factorization.

991356641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 318751.

The product of its digits is 174960, while the sum is 44.

The square root of 991356641 is about 31485.8165052139. The cubic root of 991356641 is about 997.1105393921.

The spelling of 991356641 in words is "nine hundred ninety-one million, three hundred fifty-six thousand, six hundred forty-one".