81219465681 has 8 divisors (see below), whose sum is σ = 108769681824. Its totient is φ = 53907780000.

The previous prime is 81219465617. The next prime is 81219465707. The reversal of 81219465681 is 18656491218.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81219465681 - 2⁶ = 81219465617 is a prime.

It is a super-2 number, since 2×81219465681² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81219465181) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 59631820 + ... + 59633181.

It is an arithmetic number, because the mean of its divisors is an integer number (13596210228).

Almost surely, 2^81219465681 is an apocalyptic number.

It is an amenable number.

81219465681 is a deficient number, since it is larger than the sum of its proper divisors (27550216143).

81219465681 is a wasteful number, since it uses less digits than its factorization.

81219465681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 119265231.

The product of its digits is 829440, while the sum is 51.

The spelling of 81219465681 in words is "eighty-one billion, two hundred nineteen million, four hundred sixty-five thousand, six hundred eighty-one".