67215451721 has 6 divisors (see below), whose sum is σ = 73881447066. Its totient is φ = 61104956000.

The previous prime is 67215451679. The next prime is 67215451727. The reversal of 67215451721 is 12715451276.

It can be written as a sum of positive squares in only one way, i.e., 65689690000 + 1525761721 = 256300^2 + 39061^2 .

It is a de Polignac number, because none of the positive numbers 2^k-67215451721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (67215451727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 277749680 + ... + 277749921.

It is an arithmetic number, because the mean of its divisors is an integer number (12313574511).

Almost surely, 2^67215451721 is an apocalyptic number.

It is an amenable number.

67215451721 is a deficient number, since it is larger than the sum of its proper divisors (6665995345).

67215451721 is a wasteful number, since it uses less digits than its factorization.

67215451721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 555499623 (or 555499612 counting only the distinct ones).

The product of its digits is 117600, while the sum is 41.

The spelling of 67215451721 in words is "sixty-seven billion, two hundred fifteen million, four hundred fifty-one thousand, seven hundred twenty-one".