77999869 has 2 divisors, whose sum is σ = 77999870. Its totient is φ = 77999868.

The previous prime is 77999863. The next prime is 77999951. The reversal of 77999869 is 96899977.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73102500 + 4897369 = 8550^2 + 2213^2 .

It is an emirp because it is prime and its reverse (96899977) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77999869 - 2¹⁷ = 77868797 is a prime.

It is a super-2 number, since 2×77999869² = 12167959128034322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 77999869.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77999863) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38999934 + 38999935.

It is an arithmetic number, because the mean of its divisors is an integer number (38999935).

Almost surely, 2^77999869 is an apocalyptic number.

It is an amenable number.

77999869 is a deficient number, since it is larger than the sum of its proper divisors (1).

77999869 is an equidigital number, since it uses as much as digits as its factorization.

77999869 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15431472, while the sum is 64.

The square root of 77999869 is about 8831.7534499102. The cubic root of 77999869 is about 427.2656289738.

The spelling of 77999869 in words is "seventy-seven million, nine hundred ninety-nine thousand, eight hundred sixty-nine".