77861647369 has 9 divisors (see below), whose sum is σ = 85586837581. Its totient is φ = 70780525420.

The previous prime is 77861647361. The next prime is 77861647373. The reversal of 77861647369 is 96374616877.

The square root of 77861647369 is 279037.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 77861647369 - 2³ = 77861647361 is a prime.

It is a super-2 number, since 2×77861647369² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 77861647369.

It is not an unprimeable number, because it can be changed into a prime (77861647361) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3056724 + ... + 3082090.

Almost surely, 2^77861647369 is an apocalyptic number.

77861647369 is the 279037-th square number.

77861647369 is the 139519-th centered octagonal number.

It is an amenable number.

77861647369 is a deficient number, since it is larger than the sum of its proper divisors (7725190212).

77861647369 is an frugal number, since it uses more digits than its factorization.

77861647369 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50756 (or 25378 counting only the distinct ones).

The product of its digits is 64012032, while the sum is 64.

Multiplying 77861647369 by its sum of digits (64), we get a square (4983145431616 = 2232296²).

The spelling of 77861647369 in words is "seventy-seven billion, eight hundred sixty-one million, six hundred forty-seven thousand, three hundred sixty-nine".