77121722641556 has 6 divisors (see below), whose sum is σ = 134963014622730. Its totient is φ = 38560861320776.

The previous prime is 77121722641543. The next prime is 77121722641589. The reversal of 77121722641556 is 65514622712177.

It can be written as a sum of positive squares in only one way, i.e., 68134558061956 + 8987164579600 = 8254366^2 + 2997860^2 .

It is a super-2 number, since 2×77121722641556² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9640215330191 + ... + 9640215330198.

It is an arithmetic number, because the mean of its divisors is an integer number (22493835770455).

Almost surely, 2^{77121722641556} is an apocalyptic number.

It is an amenable number.

77121722641556 is a deficient number, since it is larger than the sum of its proper divisors (57841291981174).

77121722641556 is a wasteful number, since it uses less digits than its factorization.

77121722641556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19280430660393 (or 19280430660391 counting only the distinct ones).

The product of its digits is 9878400, while the sum is 56.

The spelling of 77121722641556 in words is "seventy-seven trillion, one hundred twenty-one billion, seven hundred twenty-two million, six hundred forty-one thousand, five hundred fifty-six".