671609991 has 32 divisors (see below), whose sum is σ = 989936640.
Its totient is φ = 402401664.
The previous prime is 671609989. The next prime is 671610013. The reversal of 671609991 is 199906176.
It is not a de Polignac number, because 671609991 - 21 = 671609989 is a prime.
It is a super-2 number, since 2×6716099912 = 902119960022040162, which contains 22 as substring.
It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.
It is a self number, because there is not a number n which added to its sum of digits gives 671609991.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (671609941) by changing a digit.
It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 933730 + ... + 934448.
It is an arithmetic number, because the mean of its divisors is an integer number (30935520).
Almost surely, 2671609991 is an apocalyptic number.
671609991 is a deficient number, since it is larger than the sum of its proper divisors (318326649).
671609991 is a wasteful number, since it uses less digits than its factorization.
671609991 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 1335.
The product of its (nonzero) digits is 183708, while the sum is 48.
The square root of 671609991 is about 25915.4392399589.
The cubic root of 671609991 is about 875.7343455945.
The spelling of 671609991 in words is "six hundred seventy-one million, six hundred nine thousand, nine hundred ninety-one".