81515755751518 has 16 divisors (see below), whose sum is σ = 133397090918784. Its totient is φ = 37050485023960.

The previous prime is 81515755751497. The next prime is 81515755751537.

81515755751518 is nontrivially palindromic in base 10.

It is a super-2 number, since 2×81515755751518² (a number of 29 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81515755751518.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 106170130 + ... + 106935157.

It is an arithmetic number, because the mean of its divisors is an integer number (8337318182424).

Almost surely, 2^{81515755751518} is an apocalyptic number.

81515755751518 is a deficient number, since it is larger than the sum of its proper divisors (51881335167266).

81515755751518 is a wasteful number, since it uses less digits than its factorization.

81515755751518 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213122687.

The product of its digits is 49000000, while the sum is 64.

The spelling of 81515755751518 in words is "eighty-one trillion, five hundred fifteen billion, seven hundred fifty-five million, seven hundred fifty-one thousand, five hundred eighteen".