64716733721 has 4 divisors (see below), whose sum is σ = 65777663844. Its totient is φ = 63655803600.

The previous prime is 64716733651. The next prime is 64716733789. The reversal of 64716733721 is 12733761746.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12733761746 = 2 ⋅6366880873.

It can be written as a sum of positive squares in 2 ways, for example, as 19842666496 + 44874067225 = 140864^2 + 211835^2 .

It is a cyclic number.

It is not a de Polignac number, because 64716733721 - 2¹⁰ = 64716732697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64716733021) 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, 530464970 + ... + 530465091.

It is an arithmetic number, because the mean of its divisors is an integer number (16444415961).

Almost surely, 2^64716733721 is an apocalyptic number.

64716733721 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

64716733721 is a deficient number, since it is larger than the sum of its proper divisors (1060930123).

64716733721 is a wasteful number, since it uses less digits than its factorization.

64716733721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1060930122.

The product of its digits is 889056, while the sum is 47.

The spelling of 64716733721 in words is "sixty-four billion, seven hundred sixteen million, seven hundred thirty-three thousand, seven hundred twenty-one".