66967921 has 2 divisors, whose sum is σ = 66967922. Its totient is φ = 66967920.

The previous prime is 66967919. The next prime is 66967939. The reversal of 66967921 is 12976966.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 53129521 + 13838400 = 7289^2 + 3720^2 .

It is a cyclic number.

It is not a de Polignac number, because 66967921 - 2¹ = 66967919 is a prime.

Together with 66967919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (66967321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33483960 + 33483961.

It is an arithmetic number, because the mean of its divisors is an integer number (33483961).

Almost surely, 2^66967921 is an apocalyptic number.

It is an amenable number.

66967921 is a deficient number, since it is larger than the sum of its proper divisors (1).

66967921 is an equidigital number, since it uses as much as digits as its factorization.

66967921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 244944, while the sum is 46.

The square root of 66967921 is about 8183.3930004614. The cubic root of 66967921 is about 406.0899786013.

The spelling of 66967921 in words is "sixty-six million, nine hundred sixty-seven thousand, nine hundred twenty-one".