991641492 has 18 divisors (see below), whose sum is σ = 2506649418. Its totient is φ = 330547152.

The previous prime is 991641479. The next prime is 991641493. The reversal of 991641492 is 294146199.

It can be written as a sum of positive squares in only one way, i.e., 606932496 + 384708996 = 24636^2 + 19614^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991641493) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 13772763 + ... + 13772834.

It is an arithmetic number, because the mean of its divisors is an integer number (139258301).

Almost surely, 2^991641492 is an apocalyptic number.

It is an amenable number.

991641492 is an abundant number, since it is smaller than the sum of its proper divisors (1515007926).

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

991641492 is a wasteful number, since it uses less digits than its factorization.

991641492 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27545607 (or 27545602 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 991641492 is about 31490.3396615534. The cubic root of 991641492 is about 997.2060316778.

The spelling of 991641492 in words is "nine hundred ninety-one million, six hundred forty-one thousand, four hundred ninety-two".