781121312021 has 8 divisors (see below), whose sum is σ = 789990178560. Its totient is φ = 772283402352.

The previous prime is 781121311963. The next prime is 781121312047. The reversal of 781121312021 is 120213121187.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 781121312021 - 2¹⁰ = 781121310997 is a prime.

It is a super-2 number, since 2×781121312021² (a number of 25 digits) 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 (781121312051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7688465 + ... + 7789398.

It is an arithmetic number, because the mean of its divisors is an integer number (98748772320).

Almost surely, 2^781121312021 is an apocalyptic number.

It is an amenable number.

781121312021 is a deficient number, since it is larger than the sum of its proper divisors (8868866539).

781121312021 is a wasteful number, since it uses less digits than its factorization.

781121312021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15478435.

The product of its (nonzero) digits is 1344, while the sum is 29.

The spelling of 781121312021 in words is "seven hundred eighty-one billion, one hundred twenty-one million, three hundred twelve thousand, twenty-one".