31720417 has 4 divisors (see below), whose sum is σ = 32011540. Its totient is φ = 31429296.

The previous prime is 31720397. The next prime is 31720421. The reversal of 31720417 is 71402713.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 71402713 = 53 ⋅1347221.

It can be written as a sum of positive squares in 2 ways, for example, as 12702096 + 19018321 = 3564^2 + 4361^2 .

It is a cyclic number.

It is not a de Polignac number, because 31720417 - 2¹⁹ = 31196129 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31720391 and 31720400.

It is not an unprimeable number, because it can be changed into a prime (31720477) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 145398 + ... + 145615.

It is an arithmetic number, because the mean of its divisors is an integer number (8002885).

Almost surely, 2^31720417 is an apocalyptic number.

It is an amenable number.

31720417 is a deficient number, since it is larger than the sum of its proper divisors (291123).

31720417 is a wasteful number, since it uses less digits than its factorization.

31720417 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 291122.

The product of its (nonzero) digits is 1176, while the sum is 25.

The square root of 31720417 is about 5632.0881562703. The cubic root of 31720417 is about 316.5528996064.

The spelling of 31720417 in words is "thirty-one million, seven hundred twenty thousand, four hundred seventeen".