21299789 has 16 divisors (see below), whose sum is σ = 25145856. Its totient is φ = 17664000.

The previous prime is 21299783. The next prime is 21299791. The reversal of 21299789 is 98799212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21299789 - 2⁸ = 21299533 is a prime.

It is a super-2 number, since 2×21299789² = 907362022889042, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (47).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21299783) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32909 + ... + 33549.

It is an arithmetic number, because the mean of its divisors is an integer number (1571616).

Almost surely, 2^21299789 is an apocalyptic number.

It is an amenable number.

21299789 is a deficient number, since it is larger than the sum of its proper divisors (3846067).

21299789 is a wasteful number, since it uses less digits than its factorization.

21299789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 796.

The product of its digits is 163296, while the sum is 47.

The square root of 21299789 is about 4615.1694443433. The cubic root of 21299789 is about 277.1990688480.

It can be divided in two parts, 212 and 99789, that added together give a palindrome (100001).

The spelling of 21299789 in words is "twenty-one million, two hundred ninety-nine thousand, seven hundred eighty-nine".