64156509320821 has 4 divisors (see below), whose sum is σ = 64581386866144. Its totient is φ = 63731631775500.

The previous prime is 64156509320819. The next prime is 64156509320879. The reversal of 64156509320821 is 12802390565146.

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 64156509320821 - 2¹ = 64156509320819 is a prime.

It is a super-2 number, since 2×64156509320821² (a number of 28 digits) 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 (64156509330821) 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, 212438772435 + ... + 212438772736.

It is an arithmetic number, because the mean of its divisors is an integer number (16145346716536).

Almost surely, 2^{64156509320821} is an apocalyptic number.

It is an amenable number.

64156509320821 is a deficient number, since it is larger than the sum of its proper divisors (424877545323).

64156509320821 is a wasteful number, since it uses less digits than its factorization.

64156509320821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 424877545322.

The product of its (nonzero) digits is 3110400, while the sum is 52.

Adding to 64156509320821 its reverse (12802390565146), we get a palindrome (76958899885967).

The spelling of 64156509320821 in words is "sixty-four trillion, one hundred fifty-six billion, five hundred nine million, three hundred twenty thousand, eight hundred twenty-one".