81220742455 has 8 divisors (see below), whose sum is σ = 97467400800. Its totient is φ = 64974920736.

The previous prime is 81220742387. The next prime is 81220742459. The reversal of 81220742455 is 55424702218.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 81220742455 - 2⁷ = 81220742327 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81220742459) 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, 29101 + ... + 404089.

It is an arithmetic number, because the mean of its divisors is an integer number (12183425100).

Almost surely, 2^81220742455 is an apocalyptic number.

81220742455 is a deficient number, since it is larger than the sum of its proper divisors (16246658345).

81220742455 is a wasteful number, since it uses less digits than its factorization.

81220742455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 418313.

The product of its (nonzero) digits is 179200, while the sum is 40.

The spelling of 81220742455 in words is "eighty-one billion, two hundred twenty million, seven hundred forty-two thousand, four hundred fifty-five".