81651025519 has 16 divisors (see below), whose sum is σ = 97028775936. Its totient is φ = 67234564800.

The previous prime is 81651025459. The next prime is 81651025523. The reversal of 81651025519 is 91552015618.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 81651025519 - 2²¹ = 81648928367 is a prime.

It is a super-2 number, since 2×81651025519² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81651025529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1343527 + ... + 1402984.

It is an arithmetic number, because the mean of its divisors is an integer number (6064298496).

Almost surely, 2^81651025519 is an apocalyptic number.

81651025519 is a deficient number, since it is larger than the sum of its proper divisors (15377750417).

81651025519 is a wasteful number, since it uses less digits than its factorization.

81651025519 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2746686.

The product of its (nonzero) digits is 108000, while the sum is 43.

Subtracting 81651025519 from its reverse (91552015618), we obtain a palindrome (9900990099).

The spelling of 81651025519 in words is "eighty-one billion, six hundred fifty-one million, twenty-five thousand, five hundred nineteen".