81451265509 has 4 divisors (see below), whose sum is σ = 85738174240. Its totient is φ = 77164356780.

The previous prime is 81451265507. The next prime is 81451265591. The reversal of 81451265509 is 90556215418.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81451265509 - 2¹ = 81451265507 is a prime.

It is a super-2 number, since 2×81451265509² (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 (81451265501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2143454337 + ... + 2143454374.

It is an arithmetic number, because the mean of its divisors is an integer number (21434543560).

Almost surely, 2^81451265509 is an apocalyptic number.

It is an amenable number.

81451265509 is a deficient number, since it is larger than the sum of its proper divisors (4286908731).

81451265509 is a wasteful number, since it uses less digits than its factorization.

81451265509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4286908730.

The product of its (nonzero) digits is 432000, while the sum is 46.

The spelling of 81451265509 in words is "eighty-one billion, four hundred fifty-one million, two hundred sixty-five thousand, five hundred nine".