781664573 has 4 divisors (see below), whose sum is σ = 827644860. Its totient is φ = 735684288.

The previous prime is 781664563. The next prime is 781664671. The reversal of 781664573 is 375466187.

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

It can be written as a sum of positive squares in 2 ways, for example, as 557054404 + 224610169 = 23602^2 + 14987^2 .

It is a cyclic number.

It is not a de Polignac number, because 781664573 - 2¹⁰ = 781663549 is a prime.

It is a super-2 number, since 2×781664573² = 1221999009366544658, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (781664563) 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, 22990118 + ... + 22990151.

It is an arithmetic number, because the mean of its divisors is an integer number (206911215).

Almost surely, 2^781664573 is an apocalyptic number.

It is an amenable number.

781664573 is a deficient number, since it is larger than the sum of its proper divisors (45980287).

781664573 is a wasteful number, since it uses less digits than its factorization.

781664573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45980286.

The product of its digits is 846720, while the sum is 47.

The square root of 781664573 is about 27958.2648424397. The cubic root of 781664573 is about 921.1707578510.

The spelling of 781664573 in words is "seven hundred eighty-one million, six hundred sixty-four thousand, five hundred seventy-three".