938693821 has 4 divisors (see below), whose sum is σ = 1010901052. Its totient is φ = 866486592.

The previous prime is 938693813. The next prime is 938693831. The reversal of 938693821 is 128396839.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 128396839 = 43 ⋅2985973.

It can be written as a sum of positive squares in 2 ways, for example, as 412496100 + 526197721 = 20310^2 + 22939^2 .

It is a cyclic number.

It is not a de Polignac number, because 938693821 - 2³ = 938693813 is a prime.

It is a super-2 number, since 2×938693821² = 1762292179167160082, 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 (938693831) 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, 36103596 + ... + 36103621.

It is an arithmetic number, because the mean of its divisors is an integer number (252725263).

Almost surely, 2^938693821 is an apocalyptic number.

It is an amenable number.

938693821 is a deficient number, since it is larger than the sum of its proper divisors (72207231).

938693821 is a wasteful number, since it uses less digits than its factorization.

938693821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72207230.

The product of its digits is 559872, while the sum is 49.

The square root of 938693821 is about 30638.1105977506. The cubic root of 938693821 is about 979.1321697394.

The spelling of 938693821 in words is "nine hundred thirty-eight million, six hundred ninety-three thousand, eight hundred twenty-one".