77813881 has 2 divisors, whose sum is σ = 77813882. Its totient is φ = 77813880.

The previous prime is 77813863. The next prime is 77813887. The reversal of 77813881 is 18831877.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59151481 + 18662400 = 7691^2 + 4320^2 .

It is an emirp because it is prime and its reverse (18831877) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77813881 - 2¹⁵ = 77781113 is a prime.

It is a super-2 number, since 2×77813881² = 12110000152564322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (77813887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38906940 + 38906941.

It is an arithmetic number, because the mean of its divisors is an integer number (38906941).

Almost surely, 2^77813881 is an apocalyptic number.

It is an amenable number.

77813881 is a deficient number, since it is larger than the sum of its proper divisors (1).

77813881 is an equidigital number, since it uses as much as digits as its factorization.

77813881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 75264, while the sum is 43.

The square root of 77813881 is about 8821.2176597112. The cubic root of 77813881 is about 426.9257586374.

The spelling of 77813881 in words is "seventy-seven million, eight hundred thirteen thousand, eight hundred eighty-one".