21381829 has 8 divisors (see below), whose sum is σ = 24494400. Its totient is φ = 18283776.

The previous prime is 21381823. The next prime is 21381839. The reversal of 21381829 is 92818312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21381829 - 2⁹ = 21381317 is a prime.

It is a super-2 number, since 2×21381829² = 914365222770482, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21381794 and 21381803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21381823) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 259 + ... + 6544.

It is an arithmetic number, because the mean of its divisors is an integer number (3061800).

Almost surely, 2^21381829 is an apocalyptic number.

It is an amenable number.

21381829 is a deficient number, since it is larger than the sum of its proper divisors (3112571).

21381829 is an equidigital number, since it uses as much as digits as its factorization.

21381829 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7259.

The product of its digits is 6912, while the sum is 34.

The square root of 21381829 is about 4624.0489833046. The cubic root of 21381829 is about 277.5545070539.

It can be divided in two parts, 2 and 1381829, that added together give a palindrome (1381831).

The spelling of 21381829 in words is "twenty-one million, three hundred eighty-one thousand, eight hundred twenty-nine".