6521945791 has 4 divisors (see below), whose sum is σ = 6530516784. Its totient is φ = 6513374800.

The previous prime is 6521945767. The next prime is 6521945813. The reversal of 6521945791 is 1975491256.

It is a happy number.

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 6521945791 - 2⁷ = 6521945663 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6521945291) 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, 4284355 + ... + 4285876.

It is an arithmetic number, because the mean of its divisors is an integer number (1632629196).

Almost surely, 2^6521945791 is an apocalyptic number.

6521945791 is a deficient number, since it is larger than the sum of its proper divisors (8570993).

6521945791 is an equidigital number, since it uses as much as digits as its factorization.

6521945791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8570992.

The product of its digits is 680400, while the sum is 49.

The square root of 6521945791 is about 80758.5648151328. The cubic root of 6521945791 is about 1868.3535500863.

The spelling of 6521945791 in words is "six billion, five hundred twenty-one million, nine hundred forty-five thousand, seven hundred ninety-one".