31399261 has 4 divisors (see below), whose sum is σ = 31796800. Its totient is φ = 31001724.

The previous prime is 31399237. The next prime is 31399367. The reversal of 31399261 is 16299313.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 16299313 = 821 ⋅19853.

It is a cyclic number.

It is not a de Polignac number, because 31399261 - 2¹¹ = 31397213 is a prime.

It is a super-2 number, since 2×31399261² = 1971827182692242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31399211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 198651 + ... + 198808.

It is an arithmetic number, because the mean of its divisors is an integer number (7949200).

Almost surely, 2^31399261 is an apocalyptic number.

It is an amenable number.

31399261 is a deficient number, since it is larger than the sum of its proper divisors (397539).

31399261 is an equidigital number, since it uses as much as digits as its factorization.

31399261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 397538.

The product of its digits is 8748, while the sum is 34.

The square root of 31399261 is about 5603.5043499582. The cubic root of 31399261 is about 315.4809516974.

The spelling of 31399261 in words is "thirty-one million, three hundred ninety-nine thousand, two hundred sixty-one".