66431281 has 4 divisors (see below), whose sum is σ = 75921472. Its totient is φ = 56941092.

The previous prime is 66431273. The next prime is 66431303. The reversal of 66431281 is 18213466.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66431281 - 2³ = 66431273 is a prime.

It is a super-2 number, since 2×66431281² = 8826230190601922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66431381) 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, 4745085 + ... + 4745098.

It is an arithmetic number, because the mean of its divisors is an integer number (18980368).

Almost surely, 2^66431281 is an apocalyptic number.

It is an amenable number.

66431281 is a deficient number, since it is larger than the sum of its proper divisors (9490191).

66431281 is an equidigital number, since it uses as much as digits as its factorization.

66431281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9490190.

The product of its digits is 6912, while the sum is 31.

The square root of 66431281 is about 8150.5386938533. The cubic root of 66431281 is about 405.0023492218.

The spelling of 66431281 in words is "sixty-six million, four hundred thirty-one thousand, two hundred eighty-one".