81644030 has 32 divisors (see below), whose sum is σ = 167577984. Its totient is φ = 28371456.

The previous prime is 81644011. The next prime is 81644033. The reversal of 81644030 is 3044618.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81644033) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16262 + ... + 20681.

It is an arithmetic number, because the mean of its divisors is an integer number (5236812).

Almost surely, 2^81644030 is an apocalyptic number.

81644030 is an abundant number, since it is smaller than the sum of its proper divisors (85933954).

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

81644030 is a wasteful number, since it uses less digits than its factorization.

81644030 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36980.

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 81644030 is about 9035.7086053060. The cubic root of 81644030 is about 433.8185760849.

Adding to 81644030 its reverse (3044618), we get a palindrome (84688648).

The spelling of 81644030 in words is "eighty-one million, six hundred forty-four thousand, thirty".