387172021 has 4 divisors (see below), whose sum is σ = 387277632. Its totient is φ = 387066412.

The previous prime is 387172007. The next prime is 387172057. The reversal of 387172021 is 120271783.

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: 120271783 = 269 ⋅447107.

It is a cyclic number.

It is not a de Polignac number, because 387172021 - 2⁷ = 387171893 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (387172081) 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, 47101 + ... + 54706.

It is an arithmetic number, because the mean of its divisors is an integer number (96819408).

Almost surely, 2^387172021 is an apocalyptic number.

It is an amenable number.

387172021 is a deficient number, since it is larger than the sum of its proper divisors (105611).

387172021 is a wasteful number, since it uses less digits than its factorization.

387172021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105610.

The product of its (nonzero) digits is 4704, while the sum is 31.

The square root of 387172021 is about 19676.6872465870. The cubic root of 387172021 is about 728.8441212123.

The spelling of 387172021 in words is "three hundred eighty-seven million, one hundred seventy-two thousand, twenty-one".