78212791 has 2 divisors, whose sum is σ = 78212792. Its totient is φ = 78212790.

The previous prime is 78212777. The next prime is 78212821. The reversal of 78212791 is 19721287.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 78212791 - 2⁷ = 78212663 is a prime.

It is a super-2 number, since 2×78212791² = 12234481352019362, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 78212791.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78212891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39106395 + 39106396.

It is an arithmetic number, because the mean of its divisors is an integer number (39106396).

Almost surely, 2^78212791 is an apocalyptic number.

78212791 is a deficient number, since it is larger than the sum of its proper divisors (1).

78212791 is an equidigital number, since it uses as much as digits as its factorization.

78212791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14112, while the sum is 37.

The square root of 78212791 is about 8843.7995793663. The cubic root of 78212791 is about 427.6540552580.

It can be divided in two parts, 78212 and 791, that added together give a triangular number (79003 = T₃₉₇).

The spelling of 78212791 in words is "seventy-eight million, two hundred twelve thousand, seven hundred ninety-one".