81273653 has 2 divisors, whose sum is σ = 81273654. Its totient is φ = 81273652.

The previous prime is 81273641. The next prime is 81273691. The reversal of 81273653 is 35637218.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74684164 + 6589489 = 8642^2 + 2567^2 .

It is a cyclic number.

It is not a de Polignac number, because 81273653 - 2⁴ = 81273637 is a prime.

It is equal to p_4739570 and since 81273653 and 4739570 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81273553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40636826 + 40636827.

It is an arithmetic number, because the mean of its divisors is an integer number (40636827).

Almost surely, 2^81273653 is an apocalyptic number.

It is an amenable number.

81273653 is a deficient number, since it is larger than the sum of its proper divisors (1).

81273653 is an equidigital number, since it uses as much as digits as its factorization.

81273653 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30240, while the sum is 35.

The square root of 81273653 is about 9015.1901255603. The cubic root of 81273653 is about 433.1615776256.

The spelling of 81273653 in words is "eighty-one million, two hundred seventy-three thousand, six hundred fifty-three".