2129381 has 4 divisors (see below), whose sum is σ = 2169612.
Its totient is φ = 2089152.
The previous prime is 2129371. The next prime is 2129389. The reversal of 2129381 is 1839212.
It is a semiprime because it is the product of two primes.
It can be written as a sum of positive squares in 2 ways, for example, as 1809025 + 320356 = 1345^2 + 566^2
It is a cyclic number.
It is not a de Polignac number, because 2129381 - 214 = 2112997 is a prime.
It is a super-2 number, since 2×21293812 = 9068526886322, which contains 22 as substring.
It is a Duffinian number.
It is a self number, because there is not a number n which added to its sum of digits gives 2129381.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (2129389) 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, 20036 + ... + 20141.
It is an arithmetic number, because the mean of its divisors is an integer number (542403).
22129381 is an apocalyptic number.
It is an amenable number.
2129381 is a deficient number, since it is larger than the sum of its proper divisors (40231).
2129381 is an equidigital number, since it uses as much as digits as its factorization.
2129381 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 40230.
The product of its digits is 864, while the sum is 26.
The square root of 2129381 is about 1459.2398706176.
The cubic root of 2129381 is about 128.6523701381.
The spelling of 2129381 in words is "two million, one hundred twenty-nine thousand, three hundred eighty-one".