81251351506 has 32 divisors (see below), whose sum is σ = 131690361600. Its totient is φ = 37375642944.

The previous prime is 81251351497. The next prime is 81251351507. The reversal of 81251351506 is 60515315218.

It is not an unprimeable number, because it can be changed into a prime (81251351507) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10759420 + ... + 10766968.

It is an arithmetic number, because the mean of its divisors is an integer number (4115323800).

Almost surely, 2^81251351506 is an apocalyptic number.

81251351506 is a deficient number, since it is larger than the sum of its proper divisors (50439010094).

81251351506 is a wasteful number, since it uses less digits than its factorization.

81251351506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8890.

The product of its (nonzero) digits is 36000, while the sum is 37.

The spelling of 81251351506 in words is "eighty-one billion, two hundred fifty-one million, three hundred fifty-one thousand, five hundred six".