31491091 has 4 divisors (see below), whose sum is σ = 31509184. Its totient is φ = 31473000.

The previous prime is 31491079. The next prime is 31491101. The reversal of 31491091 is 19019413.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 31491091 - 2¹¹ = 31489043 is a prime.

It is a super-3 number, since 3×31491091³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31491011) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6120 + ... + 10021.

It is an arithmetic number, because the mean of its divisors is an integer number (7877296).

Almost surely, 2^31491091 is an apocalyptic number.

31491091 is a deficient number, since it is larger than the sum of its proper divisors (18093).

31491091 is a wasteful number, since it uses less digits than its factorization.

31491091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18092.

The product of its (nonzero) digits is 972, while the sum is 28.

The square root of 31491091 is about 5611.6923472336. The cubic root of 31491091 is about 315.7882032936.

The spelling of 31491091 in words is "thirty-one million, four hundred ninety-one thousand, ninety-one".