81361413 has 54 divisors (see below), whose sum is σ = 141689574. Its totient is φ = 44841888.

The previous prime is 81361411. The next prime is 81361421. The reversal of 81361413 is 31416318.

It can be written as a sum of positive squares in only one way, i.e., 75220929 + 6140484 = 8673^2 + 2478^2 .

It is not a de Polignac number, because 81361413 - 2¹ = 81361411 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81361411) 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 in 53 ways as a sum of consecutive naturals, for example, 1378978 + ... + 1379036.

It is an arithmetic number, because the mean of its divisors is an integer number (2623881).

Almost surely, 2^81361413 is an apocalyptic number.

It is an amenable number.

81361413 is a deficient number, since it is larger than the sum of its proper divisors (60328161).

81361413 is a wasteful number, since it uses less digits than its factorization.

81361413 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 191 (or 122 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 81361413 is about 9020.0561528186. The cubic root of 81361413 is about 433.3174320924.

It can be divided in two parts, 813 and 61413, that added together give a palindrome (62226).

The spelling of 81361413 in words is "eighty-one million, three hundred sixty-one thousand, four hundred thirteen".