31618121 has 2 divisors, whose sum is σ = 31618122. Its totient is φ = 31618120.

The previous prime is 31618099. The next prime is 31618127. The reversal of 31618121 is 12181613.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 29822521 + 1795600 = 5461^2 + 1340^2 .

It is an emirp because it is prime and its reverse (12181613) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31618121 - 2⁶ = 31618057 is a prime.

It is not a weakly prime, because it can be changed into another prime (31618127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15809060 + 15809061.

It is an arithmetic number, because the mean of its divisors is an integer number (15809061).

Almost surely, 2^31618121 is an apocalyptic number.

It is an amenable number.

31618121 is a deficient number, since it is larger than the sum of its proper divisors (1).

31618121 is an equidigital number, since it uses as much as digits as its factorization.

31618121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 288, while the sum is 23.

The square root of 31618121 is about 5622.9992886359. Note that the first 3 decimals coincide. The cubic root of 31618121 is about 316.2122465829.

Adding to 31618121 its reverse (12181613), we get a palindrome (43799734).

The spelling of 31618121 in words is "thirty-one million, six hundred eighteen thousand, one hundred twenty-one".