6620781745 has 4 divisors (see below), whose sum is σ = 7944938100. Its totient is φ = 5296625392.

The previous prime is 6620781731. The next prime is 6620781763. The reversal of 6620781745 is 5471870266.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5471870266 = 2 ⋅2735935133.

It can be written as a sum of positive squares in 2 ways, for example, as 2937748401 + 3683033344 = 54201^2 + 60688^2 .

It is a cyclic number.

It is not a de Polignac number, because 6620781745 - 2⁷ = 6620781617 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 6620781695 and 6620781704.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 662078170 + ... + 662078179.

It is an arithmetic number, because the mean of its divisors is an integer number (1986234525).

Almost surely, 2^6620781745 is an apocalyptic number.

It is an amenable number.

6620781745 is a deficient number, since it is larger than the sum of its proper divisors (1324156355).

6620781745 is a wasteful number, since it uses less digits than its factorization.

6620781745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1324156354.

The product of its (nonzero) digits is 564480, while the sum is 46.

The square root of 6620781745 is about 81368.1863199617. The cubic root of 6620781745 is about 1877.7441768519.

The spelling of 6620781745 in words is "six billion, six hundred twenty million, seven hundred eighty-one thousand, seven hundred forty-five".