81905074 has 4 divisors (see below), whose sum is σ = 122857614. Its totient is φ = 40952536.

The previous prime is 81905071. The next prime is 81905119. The reversal of 81905074 is 47050918.

It is a happy number.

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., 68178049 + 13727025 = 8257^2 + 3705^2 .

It is a super-2 number, since 2×81905074² = 13416882293890952, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81905071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20476267 + ... + 20476270.

Almost surely, 2^81905074 is an apocalyptic number.

81905074 is a deficient number, since it is larger than the sum of its proper divisors (40952540).

81905074 is a wasteful number, since it uses less digits than its factorization.

81905074 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40952539.

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 81905074 is about 9050.1422088274. The cubic root of 81905074 is about 434.2804398412.

The spelling of 81905074 in words is "eighty-one million, nine hundred five thousand, seventy-four".