31878481 has 2 divisors, whose sum is σ = 31878482. Its totient is φ = 31878480.

The previous prime is 31878479. The next prime is 31878487. The reversal of 31878481 is 18487813.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 31820881 + 57600 = 5641^2 + 240^2 .

It is a cyclic number.

It is not a de Polignac number, because 31878481 - 2¹ = 31878479 is a prime.

It is a super-2 number, since 2×31878481² = 2032475101734722, which contains 22 as substring.

Together with 31878479, it forms a pair of twin primes.

It is equal to p_1966792 and since 31878481 and 1966792 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (31878487) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15939240 + 15939241.

It is an arithmetic number, because the mean of its divisors is an integer number (15939241).

Almost surely, 2^31878481 is an apocalyptic number.

It is an amenable number.

31878481 is a deficient number, since it is larger than the sum of its proper divisors (1).

31878481 is an equidigital number, since it uses as much as digits as its factorization.

31878481 is an evil number, because the sum of its binary digits is even.

The product of its digits is 43008, while the sum is 40.

The square root of 31878481 is about 5646.1031694435. The cubic root of 31878481 is about 317.0778268908.

The spelling of 31878481 in words is "thirty-one million, eight hundred seventy-eight thousand, four hundred eighty-one".