991985545 has 16 divisors (see below), whose sum is σ = 1205658000. Its totient is φ = 783433728.

The previous prime is 991985537. The next prime is 991985549. The reversal of 991985545 is 545589199.

It can be written as a sum of positive squares in 8 ways, for example, as 224640144 + 767345401 = 14988^2 + 27701^2 .

It is a cyclic number.

It is not a de Polignac number, because 991985545 - 2³ = 991985537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (991985549) 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, 367561 + ... + 370249.

It is an arithmetic number, because the mean of its divisors is an integer number (75353625).

Almost surely, 2^991985545 is an apocalyptic number.

It is an amenable number.

991985545 is a deficient number, since it is larger than the sum of its proper divisors (213672455).

991985545 is a wasteful number, since it uses less digits than its factorization.

991985545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3612.

The product of its digits is 2916000, while the sum is 55.

The square root of 991985545 is about 31495.8020218568. The cubic root of 991985545 is about 997.3213462205.

The spelling of 991985545 in words is "nine hundred ninety-one million, nine hundred eighty-five thousand, five hundred forty-five".