81949477 has 2 divisors, whose sum is σ = 81949478. Its totient is φ = 81949476.

The previous prime is 81949471. The next prime is 81949493. The reversal of 81949477 is 77494918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 58967041 + 22982436 = 7679^2 + 4794^2 .

It is a cyclic number.

It is not a de Polignac number, because 81949477 - 2²³ = 73560869 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81949477.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81949471) 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, 40974738 + 40974739.

It is an arithmetic number, because the mean of its divisors is an integer number (40974739).

Almost surely, 2^81949477 is an apocalyptic number.

It is an amenable number.

81949477 is a deficient number, since it is larger than the sum of its proper divisors (1).

81949477 is an equidigital number, since it uses as much as digits as its factorization.

81949477 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 508032, while the sum is 49.

The square root of 81949477 is about 9052.5950423069. The cubic root of 81949477 is about 434.3589041324.

It can be divided in two parts, 8194 and 9477, that added together give a palindrome (17671).

The spelling of 81949477 in words is "eighty-one million, nine hundred forty-nine thousand, four hundred seventy-seven".