21869829 has 12 divisors (see below), whose sum is σ = 31648032. Its totient is φ = 14553000.

The previous prime is 21869821. The next prime is 21869839. The reversal of 21869829 is 92896812.

It is not a de Polignac number, because 21869829 - 2³ = 21869821 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21869821) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3754 + ... + 7604.

It is an arithmetic number, because the mean of its divisors is an integer number (2637336).

Almost surely, 2^21869829 is an apocalyptic number.

It is an amenable number.

21869829 is a deficient number, since it is larger than the sum of its proper divisors (9778203).

21869829 is a wasteful number, since it uses less digits than its factorization.

21869829 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4488 (or 4485 counting only the distinct ones).

The product of its digits is 124416, while the sum is 45.

The square root of 21869829 is about 4676.5188976417. The cubic root of 21869829 is about 279.6501966769.

The spelling of 21869829 in words is "twenty-one million, eight hundred sixty-nine thousand, eight hundred twenty-nine".