64509491 has 2 divisors, whose sum is σ = 64509492. Its totient is φ = 64509490.

The previous prime is 64509461. The next prime is 64509493. The reversal of 64509491 is 19490546.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 64509491 - 2¹⁰ = 64508467 is a prime.

It is a super-2 number, since 2×64509491² = 8322948858158162, which contains 22 as substring.

Together with 64509493, 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 (64509493) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32254745 + 32254746.

It is an arithmetic number, because the mean of its divisors is an integer number (32254746).

Almost surely, 2^64509491 is an apocalyptic number.

64509491 is a deficient number, since it is larger than the sum of its proper divisors (1).

64509491 is an equidigital number, since it uses as much as digits as its factorization.

64509491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 38880, while the sum is 38.

The square root of 64509491 is about 8031.7800642199. The cubic root of 64509491 is about 401.0586353397.

The spelling of 64509491 in words is "sixty-four million, five hundred nine thousand, four hundred ninety-one".