87189779 has 2 divisors, whose sum is σ = 87189780. Its totient is φ = 87189778.

The previous prime is 87189769. The next prime is 87189811. The reversal of 87189779 is 97798178.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 87189779 - 2²⁰ = 86141203 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (87189709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43594889 + 43594890.

It is an arithmetic number, because the mean of its divisors is an integer number (43594890).

Almost surely, 2^87189779 is an apocalyptic number.

87189779 is a deficient number, since it is larger than the sum of its proper divisors (1).

87189779 is an equidigital number, since it uses as much as digits as its factorization.

87189779 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 87189779 is about 9337.5467334841. The cubic root of 87189779 is about 443.4267196693.

The spelling of 87189779 in words is "eighty-seven million, one hundred eighty-nine thousand, seven hundred seventy-nine".