81373553 has 2 divisors, whose sum is σ = 81373554. Its totient is φ = 81373552.

The previous prime is 81373549. The next prime is 81373559. The reversal of 81373553 is 35537318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77563249 + 3810304 = 8807^2 + 1952^2 .

It is a cyclic number.

It is not a de Polignac number, because 81373553 - 2² = 81373549 is a prime.

It is not a weakly prime, because it can be changed into another prime (81373559) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40686776 + 40686777.

It is an arithmetic number, because the mean of its divisors is an integer number (40686777).

Almost surely, 2^81373553 is an apocalyptic number.

It is an amenable number.

81373553 is a deficient number, since it is larger than the sum of its proper divisors (1).

81373553 is an equidigital number, since it uses as much as digits as its factorization.

81373553 is an evil number, because the sum of its binary digits is even.

The product of its digits is 37800, while the sum is 35.

The square root of 81373553 is about 9020.7290725307. The cubic root of 81373553 is about 433.3389828981.

The spelling of 81373553 in words is "eighty-one million, three hundred seventy-three thousand, five hundred fifty-three".