6721511378 has 16 divisors (see below), whose sum is σ = 10178444760. Its totient is φ = 3328718976.

The previous prime is 6721511333. The next prime is 6721511387. The reversal of 6721511378 is 8731151276.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 6293724889 + 427786489 = 79333^2 + 20683^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1103750 + ... + 1109822.

Almost surely, 2^6721511378 is an apocalyptic number.

6721511378 is a deficient number, since it is larger than the sum of its proper divisors (3456933382).

6721511378 is a wasteful number, since it uses less digits than its factorization.

6721511378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11261.

The product of its digits is 70560, while the sum is 41.

The square root of 6721511378 is about 81984.8240712877. The cubic root of 6721511378 is about 1887.2190541189.

The spelling of 6721511378 in words is "six billion, seven hundred twenty-one million, five hundred eleven thousand, three hundred seventy-eight".