81954436 has 6 divisors (see below), whose sum is σ = 143420270. Its totient is φ = 40977216.

The previous prime is 81954419. The next prime is 81954437. The reversal of 81954436 is 63445918.

It can be written as a sum of positive squares in only one way, i.e., 81108036 + 846400 = 9006^2 + 920^2 .

It is not an unprimeable number, because it can be changed into a prime (81954437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10244301 + ... + 10244308.

Almost surely, 2^81954436 is an apocalyptic number.

It is an amenable number.

81954436 is a deficient number, since it is larger than the sum of its proper divisors (61465834).

81954436 is a wasteful number, since it uses less digits than its factorization.

81954436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20488613 (or 20488611 counting only the distinct ones).

The product of its digits is 103680, while the sum is 40.

The square root of 81954436 is about 9052.8689375247. The cubic root of 81954436 is about 434.3676653938.

It can be divided in two parts, 819 and 54436, that added together give a palindrome (55255).

The spelling of 81954436 in words is "eighty-one million, nine hundred fifty-four thousand, four hundred thirty-six".