81306770 has 16 divisors (see below), whose sum is σ = 149114520. Its totient is φ = 31908864.

The previous prime is 81306737. The next prime is 81306781. The reversal of 81306770 is 7760318.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 79691329 + 1615441 = 8927^2 + 1271^2 .

It is a super-2 number, since 2×81306770² = 13221581695665800, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76175 + ... + 77234.

Almost surely, 2^81306770 is an apocalyptic number.

81306770 is a deficient number, since it is larger than the sum of its proper divisors (67807750).

81306770 is a wasteful number, since it uses less digits than its factorization.

81306770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153469.

The product of its (nonzero) digits is 7056, while the sum is 32.

The square root of 81306770 is about 9017.0266718026. The cubic root of 81306770 is about 433.2204038400.

The spelling of 81306770 in words is "eighty-one million, three hundred six thousand, seven hundred seventy".