921385681 has 4 divisors (see below), whose sum is σ = 961445952. Its totient is φ = 881325412.

The previous prime is 921385679. The next prime is 921385693. The reversal of 921385681 is 186583129.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 921385681 - 2¹ = 921385679 is a prime.

It is a super-3 number, since 3×921385681³ (a number of 28 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (921385631) 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, 20030101 + ... + 20030146.

It is an arithmetic number, because the mean of its divisors is an integer number (240361488).

Almost surely, 2^921385681 is an apocalyptic number.

It is an amenable number.

921385681 is a deficient number, since it is larger than the sum of its proper divisors (40060271).

921385681 is a wasteful number, since it uses less digits than its factorization.

921385681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40060270.

The product of its digits is 103680, while the sum is 43.

The square root of 921385681 is about 30354.3354564056. The cubic root of 921385681 is about 973.0768775957.

The spelling of 921385681 in words is "nine hundred twenty-one million, three hundred eighty-five thousand, six hundred eighty-one".