31603381 has 2 divisors, whose sum is σ = 31603382. Its totient is φ = 31603380.

The previous prime is 31603367. The next prime is 31603393. The reversal of 31603381 is 18330613.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19000881 + 12602500 = 4359^2 + 3550^2 .

It is a cyclic number.

It is not a de Polignac number, because 31603381 - 2¹³ = 31595189 is a prime.

It is a super-3 number, since 3×31603381³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is equal to p_1950820 and since 31603381 and 1950820 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31603361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15801690 + 15801691.

It is an arithmetic number, because the mean of its divisors is an integer number (15801691).

Almost surely, 2^31603381 is an apocalyptic number.

It is an amenable number.

31603381 is a deficient number, since it is larger than the sum of its proper divisors (1).

31603381 is an equidigital number, since it uses as much as digits as its factorization.

31603381 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 31603381 is about 5621.6884474329. The cubic root of 31603381 is about 316.1631007888.

Adding to 31603381 its reverse (18330613), we get a palindrome (49933994).

The spelling of 31603381 in words is "thirty-one million, six hundred three thousand, three hundred eighty-one".