81678782025 has 189 divisors, whose sum is σ = 159453838479. Its totient is φ = 41483715840.

The previous prime is 81678781991. The next prime is 81678782057. The reversal of 81678782025 is 52028787618.

The square root of 81678782025 is 285795.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 13 ways, for example, as 44888473161 + 36790308864 = 211869^2 + 191808^2 .

It is a de Polignac number, because none of the positive numbers 2^k-81678782025 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 188 ways as a sum of consecutive naturals, for example, 1118887389 + ... + 1118887461.

Almost surely, 2^81678782025 is an apocalyptic number.

81678782025 is the 285795-th square number.

81678782025 is the 142898-th centered octagonal number.

It is an amenable number.

81678782025 is a deficient number, since it is larger than the sum of its proper divisors (77775056454).

81678782025 is an frugal number, since it uses more digits than its factorization.

81678782025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232 (or 110 counting only the distinct ones).

The product of its (nonzero) digits is 3010560, while the sum is 54.

The spelling of 81678782025 in words is "eighty-one billion, six hundred seventy-eight million, seven hundred eighty-two thousand, twenty-five".