81383188 has 6 divisors (see below), whose sum is σ = 142420586. Its totient is φ = 40691592.

The previous prime is 81383173. The next prime is 81383189. The reversal of 81383188 is 88138318.

It can be written as a sum of positive squares in only one way, i.e., 69189124 + 12194064 = 8318^2 + 3492^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81383188.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81383189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10172895 + ... + 10172902.

Almost surely, 2^81383188 is an apocalyptic number.

It is an amenable number.

81383188 is a deficient number, since it is larger than the sum of its proper divisors (61037398).

81383188 is a wasteful number, since it uses less digits than its factorization.

81383188 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20345801 (or 20345799 counting only the distinct ones).

The product of its digits is 36864, while the sum is 40.

The square root of 81383188 is about 9021.2631044660. The cubic root of 81383188 is about 433.3560853274.

The spelling of 81383188 in words is "eighty-one million, three hundred eighty-three thousand, one hundred eighty-eight".