81629786 has 12 divisors (see below), whose sum is σ = 142435818. Its totient is φ = 34984152.

The previous prime is 81629777. The next prime is 81629827. The reversal of 81629786 is 68792618.

It can be written as a sum of positive squares in only one way, i.e., 59830225 + 21799561 = 7735^2 + 4669^2 .

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81629786.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 416381 + ... + 416576.

Almost surely, 2^81629786 is an apocalyptic number.

81629786 is a deficient number, since it is larger than the sum of its proper divisors (60806032).

81629786 is a wasteful number, since it uses less digits than its factorization.

81629786 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 832973 (or 832966 counting only the distinct ones).

The product of its digits is 290304, while the sum is 47.

The square root of 81629786 is about 9034.9203648953. The cubic root of 81629786 is about 433.7933459438.

The spelling of 81629786 in words is "eighty-one million, six hundred twenty-nine thousand, seven hundred eighty-six".