78189779 has 2 divisors, whose sum is σ = 78189780. Its totient is φ = 78189778.

The previous prime is 78189751. The next prime is 78189791. The reversal of 78189779 is 97798187.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78189779 - 2¹⁶ = 78124243 is a prime.

It is a super-2 number, since 2×78189779² = 12227283080137682, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78180779) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39094889 + 39094890.

It is an arithmetic number, because the mean of its divisors is an integer number (39094890).

Almost surely, 2^78189779 is an apocalyptic number.

78189779 is a deficient number, since it is larger than the sum of its proper divisors (1).

78189779 is an equidigital number, since it uses as much as digits as its factorization.

78189779 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1778112, while the sum is 56.

The square root of 78189779 is about 8842.4984591460. The cubic root of 78189779 is about 427.6121092612.

The spelling of 78189779 in words is "seventy-eight million, one hundred eighty-nine thousand, seven hundred seventy-nine".