31389661 has 2 divisors, whose sum is σ = 31389662. Its totient is φ = 31389660.

The previous prime is 31389649. The next prime is 31389671. The reversal of 31389661 is 16698313.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26327161 + 5062500 = 5131^2 + 2250^2 .

It is a cyclic number.

It is not a de Polignac number, because 31389661 - 2¹¹ = 31387613 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31389661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31389601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15694830 + 15694831.

It is an arithmetic number, because the mean of its divisors is an integer number (15694831).

Almost surely, 2^31389661 is an apocalyptic number.

It is an amenable number.

31389661 is a deficient number, since it is larger than the sum of its proper divisors (1).

31389661 is an equidigital number, since it uses as much as digits as its factorization.

31389661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23328, while the sum is 37.

The square root of 31389661 is about 5602.6476776610. The cubic root of 31389661 is about 315.4487967384.

The spelling of 31389661 in words is "thirty-one million, three hundred eighty-nine thousand, six hundred sixty-one".