381521 has 4 divisors (see below), whose sum is σ = 436032. Its totient is φ = 327012.

The previous prime is 381509. The next prime is 381523. The reversal of 381521 is 125183.

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 not a de Polignac number, because 381521 - 2¹⁴ = 365137 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 381493 and 381502.

It is not an unprimeable number, because it can be changed into a prime (381523) 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, 27245 + ... + 27258.

It is an arithmetic number, because the mean of its divisors is an integer number (109008).

2³⁸¹⁵²¹ is an apocalyptic number.

It is an amenable number.

381521 is a deficient number, since it is larger than the sum of its proper divisors (54511).

381521 is an equidigital number, since it uses as much as digits as its factorization.

381521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54510.

The product of its digits is 240, while the sum is 20.

The square root of 381521 is about 617.6738621635. The cubic root of 381521 is about 72.5280747394.

Subtracting from 381521 its sum of digits (20), we obtain a triangular number (381501 = T₈₇₃).

The spelling of 381521 in words is "three hundred eighty-one thousand, five hundred twenty-one".