938172821 has 4 divisors (see below), whose sum is σ = 949476192. Its totient is φ = 926869452.

The previous prime is 938172817. The next prime is 938172827. The reversal of 938172821 is 128271839.

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, and also an emirpimes, since its reverse is a distinct semiprime: 128271839 = 10771 ⋅11909.

It is a cyclic number.

It is not a de Polignac number, because 938172821 - 2² = 938172817 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (938172827) 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, 5651561 + ... + 5651726.

It is an arithmetic number, because the mean of its divisors is an integer number (237369048).

Almost surely, 2^938172821 is an apocalyptic number.

It is an amenable number.

938172821 is a deficient number, since it is larger than the sum of its proper divisors (11303371).

938172821 is a wasteful number, since it uses less digits than its factorization.

938172821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11303370.

The product of its digits is 48384, while the sum is 41.

The square root of 938172821 is about 30629.6069351208. The cubic root of 938172821 is about 978.9509880959.

The spelling of 938172821 in words is "nine hundred thirty-eight million, one hundred seventy-two thousand, eight hundred twenty-one".