6561917387 has 4 divisors (see below), whose sum is σ = 6907281480. Its totient is φ = 6216553296.

The previous prime is 6561917317. The next prime is 6561917389. The reversal of 6561917387 is 7837191656.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 6561917387 - 2¹² = 6561913291 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6561917389) 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 3 ways as a sum of consecutive naturals, for example, 172682018 + ... + 172682055.

It is an arithmetic number, because the mean of its divisors is an integer number (1726820370).

Almost surely, 2^6561917387 is an apocalyptic number.

6561917387 is a deficient number, since it is larger than the sum of its proper divisors (345364093).

6561917387 is a wasteful number, since it uses less digits than its factorization.

6561917387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 345364092.

The product of its digits is 1905120, while the sum is 53.

The square root of 6561917387 is about 81005.6626847778. The cubic root of 6561917387 is about 1872.1626905375.

The spelling of 6561917387 in words is "six billion, five hundred sixty-one million, nine hundred seventeen thousand, three hundred eighty-seven".