31378621 has 2 divisors, whose sum is σ = 31378622. Its totient is φ = 31378620.

The previous prime is 31378591. The next prime is 31378637. The reversal of 31378621 is 12687313.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21068100 + 10310521 = 4590^2 + 3211^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31378621 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31378661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15689310 + 15689311.

It is an arithmetic number, because the mean of its divisors is an integer number (15689311).

Almost surely, 2^31378621 is an apocalyptic number.

It is an amenable number.

31378621 is a deficient number, since it is larger than the sum of its proper divisors (1).

31378621 is an equidigital number, since it uses as much as digits as its factorization.

31378621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6048, while the sum is 31.

The square root of 31378621 is about 5601.6623425551. The cubic root of 31378621 is about 315.4118104297.

The spelling of 31378621 in words is "thirty-one million, three hundred seventy-eight thousand, six hundred twenty-one".