64491281 has 2 divisors, whose sum is σ = 64491282. Its totient is φ = 64491280.

The previous prime is 64491277. The next prime is 64491283. The reversal of 64491281 is 18219446.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 60590656 + 3900625 = 7784^2 + 1975^2 .

It is a cyclic number.

It is not a de Polignac number, because 64491281 - 2² = 64491277 is a prime.

It is a super-2 number, since 2×64491281² = 8318250650041922, which contains 22 as substring.

Together with 64491283, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (64491283) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32245640 + 32245641.

It is an arithmetic number, because the mean of its divisors is an integer number (32245641).

Almost surely, 2^64491281 is an apocalyptic number.

It is an amenable number.

64491281 is a deficient number, since it is larger than the sum of its proper divisors (1).

64491281 is an equidigital number, since it uses as much as digits as its factorization.

64491281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13824, while the sum is 35.

The square root of 64491281 is about 8030.6463625290. The cubic root of 64491281 is about 401.0208943037.

The spelling of 64491281 in words is "sixty-four million, four hundred ninety-one thousand, two hundred eighty-one".