66981421 has 8 divisors (see below), whose sum is σ = 74461184. Its totient is φ = 59834160.

The previous prime is 66981389. The next prime is 66981449. The reversal of 66981421 is 12418966.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 66981421 - 2⁵ = 66981389 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66985421) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 82701 + ... + 83506.

It is an arithmetic number, because the mean of its divisors is an integer number (9307648).

Almost surely, 2^66981421 is an apocalyptic number.

It is an amenable number.

66981421 is a deficient number, since it is larger than the sum of its proper divisors (7479763).

66981421 is a wasteful number, since it uses less digits than its factorization.

66981421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166251.

The product of its digits is 20736, while the sum is 37.

The square root of 66981421 is about 8184.2178001322. The cubic root of 66981421 is about 406.1172645330.

The spelling of 66981421 in words is "sixty-six million, nine hundred eighty-one thousand, four hundred twenty-one".