66777899 has 4 divisors (see below), whose sum is σ = 67582536. Its totient is φ = 65973264.

The previous prime is 66777881. The next prime is 66777917. The reversal of 66777899 is 99877766.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (66777881) and next prime (66777917).

It is a cyclic number.

It is not a de Polignac number, because 66777899 - 2¹² = 66773803 is a prime.

It is a Duffinian number.

It is a plaindrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (66777829) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 402194 + ... + 402359.

It is an arithmetic number, because the mean of its divisors is an integer number (16895634).

Almost surely, 2^66777899 is an apocalyptic number.

66777899 is a deficient number, since it is larger than the sum of its proper divisors (804637).

66777899 is an equidigital number, since it uses as much as digits as its factorization.

66777899 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 804636.

The product of its digits is 8001504, while the sum is 59.

The square root of 66777899 is about 8171.7745318872. The cubic root of 66777899 is about 405.7055202395.

It can be divided in two parts, 66777 and 899, that added together give a palindrome (67676).

The spelling of 66777899 in words is "sixty-six million, seven hundred seventy-seven thousand, eight hundred ninety-nine".