81253213 has 4 divisors (see below), whose sum is σ = 81310588. Its totient is φ = 81195840.

The previous prime is 81253199. The next prime is 81253219. The reversal of 81253213 is 31235218.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 79619929 + 1633284 = 8923^2 + 1278^2 .

It is a cyclic number.

It is not a de Polignac number, because 81253213 - 2⁹ = 81252701 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81253219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26508 + ... + 29413.

It is an arithmetic number, because the mean of its divisors is an integer number (20327647).

Almost surely, 2^81253213 is an apocalyptic number.

It is an amenable number.

81253213 is a deficient number, since it is larger than the sum of its proper divisors (57375).

81253213 is a wasteful number, since it uses less digits than its factorization.

81253213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57374.

The product of its digits is 1440, while the sum is 25.

The square root of 81253213 is about 9014.0564120711. The cubic root of 81253213 is about 433.1252617772.

The spelling of 81253213 in words is "eighty-one million, two hundred fifty-three thousand, two hundred thirteen".