785621640609 has 27 divisors (see below), whose sum is σ = 1228846892403. Its totient is φ = 483438198672.

The previous prime is 785621640569. The next prime is 785621640631. The reversal of 785621640609 is 906046126587.

The square root of 785621640609 is 886353.

It is a perfect power (a square), and thus also a powerful number.

785621640609 is a `hidden beast` number, since 7 + 8 + 5 + 6 + 21 + 6 + 4 + 0 + 609 = 666.

It can be written as a sum of positive squares in only one way, i.e., 116216219025 + 669405421584 = 340905^2 + 818172^2 .

It is not a de Polignac number, because 785621640609 - 2⁷ = 785621640481 is a prime.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (785621640649) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 34556404 + ... + 34579130.

Almost surely, 2^785621640609 is an apocalyptic number.

785621640609 is the 886353-rd square number.

785621640609 is the 443177-th centered octagonal number.

It is an amenable number.

785621640609 is a deficient number, since it is larger than the sum of its proper divisors (443225251794).

785621640609 is an frugal number, since it uses more digits than its factorization.

785621640609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45486 (or 22743 counting only the distinct ones).

The product of its (nonzero) digits is 4354560, while the sum is 54.

It can be divided in two parts, 78562 and 1640609, that added together give a palindrome (1719171).

The spelling of 785621640609 in words is "seven hundred eighty-five billion, six hundred twenty-one million, six hundred forty thousand, six hundred nine".