81387937 has 2 divisors, whose sum is σ = 81387938. Its totient is φ = 81387936.

The previous prime is 81387931. The next prime is 81387983. The reversal of 81387937 is 73978318.

It is a happy number.

It is an a-pointer prime, because the next prime (81387983) can be obtained adding 81387937 to its sum of digits (46).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42562576 + 38825361 = 6524^2 + 6231^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81387937 is a prime.

It is not a weakly prime, because it can be changed into another prime (81387931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40693968 + 40693969.

It is an arithmetic number, because the mean of its divisors is an integer number (40693969).

Almost surely, 2^81387937 is an apocalyptic number.

It is an amenable number.

81387937 is a deficient number, since it is larger than the sum of its proper divisors (1).

81387937 is an equidigital number, since it uses as much as digits as its factorization.

81387937 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 254016, while the sum is 46.

The square root of 81387937 is about 9021.5263121048. The cubic root of 81387937 is about 433.3645144558.

The spelling of 81387937 in words is "eighty-one million, three hundred eighty-seven thousand, nine hundred thirty-seven".