775721666 has 8 divisors (see below), whose sum is σ = 1169097744. Its totient is φ = 386022420.

The previous prime is 775721663. The next prime is 775721669. The reversal of 775721666 is 666127577.

It is an interprime number because it is at equal distance from previous prime (775721663) and next prime (775721669).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 775721666.

It is not an unprimeable number, because it can be changed into a prime (775721663) 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, 918680 + ... + 919523.

It is an arithmetic number, because the mean of its divisors is an integer number (146137218).

Almost surely, 2^775721666 is an apocalyptic number.

775721666 is a deficient number, since it is larger than the sum of its proper divisors (393376078).

775721666 is a wasteful number, since it uses less digits than its factorization.

775721666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1838416.

The product of its digits is 740880, while the sum is 47.

The square root of 775721666 is about 27851.7803021638. The cubic root of 775721666 is about 918.8302974785.

The spelling of 775721666 in words is "seven hundred seventy-five million, seven hundred twenty-one thousand, six hundred sixty-six".