81261618 has 16 divisors (see below), whose sum is σ = 162717120. Its totient is φ = 27054896.

The previous prime is 81261617. The next prime is 81261619. The reversal of 81261618 is 81616218.

It is an interprime number because it is at equal distance from previous prime (81261617) and next prime (81261619).

It is not an unprimeable number, because it can be changed into a prime (81261617) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2313 + ... + 12956.

It is an arithmetic number, because the mean of its divisors is an integer number (10169820).

Almost surely, 2^81261618 is an apocalyptic number.

81261618 is an abundant number, since it is smaller than the sum of its proper divisors (81455502).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81261618 is a wasteful number, since it uses less digits than its factorization.

81261618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16161.

The product of its digits is 4608, while the sum is 33.

The square root of 81261618 is about 9014.5226163120. The cubic root of 81261618 is about 433.1401957192.

The spelling of 81261618 in words is "eighty-one million, two hundred sixty-one thousand, six hundred eighteen".