81542664 has 144 divisors (see below), whose sum is σ = 266093100. Its totient is φ = 22466304.

The previous prime is 81542641. The next prime is 81542677. The reversal of 81542664 is 46624518.

It can be written as a sum of positive squares in 2 ways, for example, as 81540900 + 1764 = 9030^2 + 42^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 101914 + ... + 102710.

Almost surely, 2^81542664 is an apocalyptic number.

81542664 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81542664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (133046550).

81542664 is an abundant number, since it is smaller than the sum of its proper divisors (184550436).

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

81542664 is a wasteful number, since it uses less digits than its factorization.

81542664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 852 (or 838 counting only the distinct ones).

The product of its digits is 46080, while the sum is 36.

The square root of 81542664 is about 9030.0976738904. The cubic root of 81542664 is about 433.6389644001.

The spelling of 81542664 in words is "eighty-one million, five hundred forty-two thousand, six hundred sixty-four".