78219217477 has 2 divisors, whose sum is σ = 78219217478. Its totient is φ = 78219217476.

The previous prime is 78219217403. The next prime is 78219217481. The reversal of 78219217477 is 77471291287.

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., 59512090401 + 18707127076 = 243951^2 + 136774^2 .

It is a cyclic number.

It is not a de Polignac number, because 78219217477 - 2¹⁵ = 78219184709 is a prime.

It is a super-2 number, since 2×78219217477² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78219217777) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39109608738 + 39109608739.

It is an arithmetic number, because the mean of its divisors is an integer number (39109608739).

Almost surely, 2^78219217477 is an apocalyptic number.

It is an amenable number.

78219217477 is a deficient number, since it is larger than the sum of its proper divisors (1).

78219217477 is an equidigital number, since it uses as much as digits as its factorization.

78219217477 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2765952, while the sum is 55.

The spelling of 78219217477 in words is "seventy-eight billion, two hundred nineteen million, two hundred seventeen thousand, four hundred seventy-seven".