64705781 has 4 divisors (see below), whose sum is σ = 73949472. Its totient is φ = 55462092.

The previous prime is 64705769. The next prime is 64705787. The reversal of 64705781 is 18750746.

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 not a de Polignac number, because 64705781 - 2⁶ = 64705717 is a prime.

It is a super-2 number, since 2×64705781² = 8373676189639922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64705787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4621835 + ... + 4621848.

It is an arithmetic number, because the mean of its divisors is an integer number (18487368).

Almost surely, 2^64705781 is an apocalyptic number.

It is an amenable number.

64705781 is a deficient number, since it is larger than the sum of its proper divisors (9243691).

64705781 is an equidigital number, since it uses as much as digits as its factorization.

64705781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9243690.

The product of its (nonzero) digits is 47040, while the sum is 38.

The square root of 64705781 is about 8043.9903654840. The cubic root of 64705781 is about 401.4650049342.

The spelling of 64705781 in words is "sixty-four million, seven hundred five thousand, seven hundred eighty-one".