21029109 has 8 divisors (see below), whose sum is σ = 28316832. Its totient is φ = 13880400.

The previous prime is 21029101. The next prime is 21029111. The reversal of 21029109 is 90192012.

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

It is not a de Polignac number, because 21029109 - 2³ = 21029101 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21029101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34399 + ... + 35004.

It is an arithmetic number, because the mean of its divisors is an integer number (3539604).

Almost surely, 2^21029109 is an apocalyptic number.

It is an amenable number.

21029109 is a deficient number, since it is larger than the sum of its proper divisors (7287723).

21029109 is a wasteful number, since it uses less digits than its factorization.

21029109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69507.

The product of its (nonzero) digits is 324, while the sum is 24.

The square root of 21029109 is about 4585.7506473859. The cubic root of 21029109 is about 276.0198342184.

It can be divided in two parts, 2102 and 9109, that added together give a palindrome (11211).

The spelling of 21029109 in words is "twenty-one million, twenty-nine thousand, one hundred nine".