81006509146 has 4 divisors (see below), whose sum is σ = 121509763722. Its totient is φ = 40503254572.

The previous prime is 81006509119. The next prime is 81006509149. The reversal of 81006509146 is 64190560018.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 45948066025 + 35058443121 = 214355^2 + 187239^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 81006509099 and 81006509108.

It is not an unprimeable number, because it can be changed into a prime (81006509149) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20251627285 + ... + 20251627288.

Almost surely, 2^81006509146 is an apocalyptic number.

81006509146 is a deficient number, since it is larger than the sum of its proper divisors (40503254576).

81006509146 is a wasteful number, since it uses less digits than its factorization.

81006509146 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40503254575.

The product of its (nonzero) digits is 51840, while the sum is 40.

The spelling of 81006509146 in words is "eighty-one billion, six million, five hundred nine thousand, one hundred forty-six".