66768021 has 6 divisors (see below), whose sum is σ = 96442710. Its totient is φ = 44512008.

The previous prime is 66767983. The next prime is 66768029. The reversal of 66768021 is 12086766.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 54552996 + 12215025 = 7386^2 + 3495^2 .

It is not a de Polignac number, because 66768021 - 2⁹ = 66767509 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66768029) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3709326 + ... + 3709343.

It is an arithmetic number, because the mean of its divisors is an integer number (16073785).

Almost surely, 2^66768021 is an apocalyptic number.

It is an amenable number.

66768021 is a deficient number, since it is larger than the sum of its proper divisors (29674689).

66768021 is a wasteful number, since it uses less digits than its factorization.

66768021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7418675 (or 7418672 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 66768021 is about 8171.1701120464. The cubic root of 66768021 is about 405.6855148345.

The spelling of 66768021 in words is "sixty-six million, seven hundred sixty-eight thousand, twenty-one".