781661562587 has 4 divisors (see below), whose sum is σ = 787367121576. Its totient is φ = 775956003600.

The previous prime is 781661562551. The next prime is 781661562607. The reversal of 781661562587 is 785265166187.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 785265166187 = 43 ⋅18261980609.

It is a cyclic number.

It is not a de Polignac number, because 781661562587 - 2¹⁸ = 781661300443 is a prime.

It is a super-2 number, since 2×781661562587² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (781661562547) 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, 2852779289 + ... + 2852779562.

It is an arithmetic number, because the mean of its divisors is an integer number (196841780394).

Almost surely, 2^781661562587 is an apocalyptic number.

781661562587 is a deficient number, since it is larger than the sum of its proper divisors (5705558989).

781661562587 is a wasteful number, since it uses less digits than its factorization.

781661562587 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5705558988.

The product of its digits is 33868800, while the sum is 62.

The spelling of 781661562587 in words is "seven hundred eighty-one billion, six hundred sixty-one million, five hundred sixty-two thousand, five hundred eighty-seven".