81421551079 has 8 divisors (see below), whose sum is σ = 88825820688. Its totient is φ = 74017666560.

The previous prime is 81421551053. The next prime is 81421551089. The reversal of 81421551079 is 97015512418.

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 81421551079 - 2⁵ = 81421551047 is a prime.

It is a super-2 number, since 2×81421551079² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81421551019) 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, 514119 + ... + 653575.

It is an arithmetic number, because the mean of its divisors is an integer number (11103227586).

Almost surely, 2^81421551079 is an apocalyptic number.

81421551079 is a deficient number, since it is larger than the sum of its proper divisors (7404269609).

81421551079 is a wasteful number, since it uses less digits than its factorization.

81421551079 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192545.

The product of its (nonzero) digits is 100800, while the sum is 43.

The spelling of 81421551079 in words is "eighty-one billion, four hundred twenty-one million, five hundred fifty-one thousand, seventy-nine".