31491 has 6 divisors (see below), whose sum is σ = 45500. Its totient is φ = 20988.
The previous prime is 31489. The next prime is 31511. The reversal of 31491 is 19413.
It is not a de Polignac number, because 31491 - 21 = 31489 is a prime.
It is a Duffinian number.
31491 is a lucky number.
It is a plaindrome in base 13.
It is not an unprimeable number, because it can be changed into a prime (31481) 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, 1741 + ... + 1758.
231491 is an apocalyptic number.
31491 is a deficient number, since it is larger than the sum of its proper divisors (14009).
31491 is a wasteful number, since it uses less digits than its factorization.
31491 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 3505 (or 3502 counting only the distinct ones).
The product of its digits is 108, while the sum is 18.
The square root of 31491 is about 177.4570370540. The cubic root of 31491 is about 31.5787899115.
The spelling of 31491 in words is "thirty-one thousand, four hundred ninety-one".
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