77245640761 has 9 divisors (see below), whose sum is σ = 77543334831. Its totient is φ = 76949088384.

The previous prime is 77245640743. The next prime is 77245640809. The reversal of 77245640761 is 16704654277.

The square root of 77245640761 is 277931.

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

It can be written as a sum of positive squares in only one way, i.e., 47205818361 + 30039822400 = 217269^2 + 173320^2 .

It is not a de Polignac number, because 77245640761 - 2¹⁵ = 77245607993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77245640711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 124790710 + ... + 124791328.

Almost surely, 2^77245640761 is an apocalyptic number.

77245640761 is the 277931-st square number.

77245640761 is the 138966-th centered octagonal number.

It is an amenable number.

77245640761 is a deficient number, since it is larger than the sum of its proper divisors (297694070).

77245640761 is an frugal number, since it uses more digits than its factorization.

77245640761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2136 (or 1068 counting only the distinct ones).

The product of its (nonzero) digits is 1975680, while the sum is 49.

Multiplying 77245640761 by its sum of digits (49), we get a square (3785036397289 = 1945517²).

The spelling of 77245640761 in words is "seventy-seven billion, two hundred forty-five million, six hundred forty thousand, seven hundred sixty-one".