81612437 has 2 divisors, whose sum is σ = 81612438. Its totient is φ = 81612436.

The previous prime is 81612403. The next prime is 81612439. The reversal of 81612437 is 73421618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 80982001 + 630436 = 8999^2 + 794^2 .

It is a cyclic number.

It is not a de Polignac number, because 81612437 - 2⁶ = 81612373 is a prime.

Together with 81612439, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81612439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40806218 + 40806219.

It is an arithmetic number, because the mean of its divisors is an integer number (40806219).

Almost surely, 2^81612437 is an apocalyptic number.

It is an amenable number.

81612437 is a deficient number, since it is larger than the sum of its proper divisors (1).

81612437 is an equidigital number, since it uses as much as digits as its factorization.

81612437 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8064, while the sum is 32.

The square root of 81612437 is about 9033.9602058012. The cubic root of 81612437 is about 433.7626120072.

The spelling of 81612437 in words is "eighty-one million, six hundred twelve thousand, four hundred thirty-seven".