81224613 has 10 divisors (see below), whose sum is σ = 121335654. Its totient is φ = 54149688.

The previous prime is 81224609. The next prime is 81224617. The reversal of 81224613 is 31642218.

It is an interprime number because it is at equal distance from previous prime (81224609) and next prime (81224617).

It can be written as a sum of positive squares in only one way, i.e., 59490369 + 21734244 = 7713^2 + 4662^2 .

It is not a de Polignac number, because 81224613 - 2² = 81224609 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81224617) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 501306 + ... + 501467.

Almost surely, 2^81224613 is an apocalyptic number.

It is an amenable number.

81224613 is a deficient number, since it is larger than the sum of its proper divisors (40111041).

81224613 is a wasteful number, since it uses less digits than its factorization.

81224613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1002785 (or 1002776 counting only the distinct ones).

The product of its digits is 2304, while the sum is 27.

The square root of 81224613 is about 9012.4698612534. The cubic root of 81224613 is about 433.0744377925.

It can be divided in two parts, 812 and 24613, that added together give a triangular number (25425 = T₂₂₅).

The spelling of 81224613 in words is "eighty-one million, two hundred twenty-four thousand, six hundred thirteen".