21828629 has 4 divisors (see below), whose sum is σ = 23112684. Its totient is φ = 20544576.

The previous prime is 21828623. The next prime is 21828659. The reversal of 21828629 is 92682812.

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 13126129 + 8702500 = 3623^2 + 2950^2 .

It is a cyclic number.

It is not a de Polignac number, because 21828629 - 2⁴ = 21828613 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21828592 and 21828601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21828623) 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, 642002 + ... + 642035.

It is an arithmetic number, because the mean of its divisors is an integer number (5778171).

Almost surely, 2^21828629 is an apocalyptic number.

It is an amenable number.

21828629 is a deficient number, since it is larger than the sum of its proper divisors (1284055).

21828629 is a wasteful number, since it uses less digits than its factorization.

21828629 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1284054.

The product of its digits is 27648, while the sum is 38.

The square root of 21828629 is about 4672.1118351341. Note that the first 3 decimals coincide. The cubic root of 21828629 is about 279.4744777179.

The spelling of 21828629 in words is "twenty-one million, eight hundred twenty-eight thousand, six hundred twenty-nine".