81340644 has 96 divisors (see below), whose sum is σ = 241790976. Its totient is φ = 20666880.

The previous prime is 81340619. The next prime is 81340657. The reversal of 81340644 is 44604318.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 42492 + ... + 44364.

It is an arithmetic number, because the mean of its divisors is an integer number (2518656).

Almost surely, 2^81340644 is an apocalyptic number.

81340644 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 81340644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120895488).

81340644 is an abundant number, since it is smaller than the sum of its proper divisors (160450332).

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

81340644 is a wasteful number, since it uses less digits than its factorization.

81340644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1945 (or 1943 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 30.

The square root of 81340644 is about 9018.9048115611. The cubic root of 81340644 is about 433.2805582014.

It can be divided in two parts, 813406 and 44, that added together give a triangular number (813450 = T₁₂₇₅).

The spelling of 81340644 in words is "eighty-one million, three hundred forty thousand, six hundred forty-four".