77834497421 has 4 divisors (see below), whose sum is σ = 78168551292. Its totient is φ = 77500443552.

The previous prime is 77834497379. The next prime is 77834497451. The reversal of 77834497421 is 12479443877.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12479443877 = 84061 ⋅148457.

It can be written as a sum of positive squares in 2 ways, for example, as 33047240521 + 44787256900 = 181789^2 + 211630^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77834497421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77834497451) 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, 167026586 + ... + 167027051.

It is an arithmetic number, because the mean of its divisors is an integer number (19542137823).

Almost surely, 2^77834497421 is an apocalyptic number.

It is an amenable number.

77834497421 is a deficient number, since it is larger than the sum of its proper divisors (334053871).

77834497421 is a wasteful number, since it uses less digits than its factorization.

77834497421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 334053870.

The product of its digits is 9483264, while the sum is 56.

The spelling of 77834497421 in words is "seventy-seven billion, eight hundred thirty-four million, four hundred ninety-seven thousand, four hundred twenty-one".