77920218981049 has 3 divisors (see below), whose sum is σ = 77920227808293. Its totient is φ = 77920210153806.

The previous prime is 77920218980911. The next prime is 77920218981053. The reversal of 77920218981049 is 94018981202977.

The square root of 77920218981049 is 8827243.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 77920218981049 - 2²⁷ = 77920084763321 is a prime.

It is a super-2 number, since 2×77920218981049² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77920218981089) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 4413622 + ... + 13240864.

It is an arithmetic number, because the mean of its divisors is an integer number (25973409269431).

Almost surely, 2^{77920218981049} is an apocalyptic number.

77920218981049 is the 8827243-rd square number.

77920218981049 is the 4413622-nd centered octagonal number.

It is an amenable number.

77920218981049 is a deficient number, since it is larger than the sum of its proper divisors (8827244).

77920218981049 is an frugal number, since it uses more digits than its factorization.

77920218981049 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17654486 (or 8827243 counting only the distinct ones).

The product of its (nonzero) digits is 36578304, while the sum is 67.

The spelling of 77920218981049 in words is "seventy-seven trillion, nine hundred twenty billion, two hundred eighteen million, nine hundred eighty-one thousand, forty-nine".