21308069 has 8 divisors (see below), whose sum is σ = 22581720. Its totient is φ = 20070400.

The previous prime is 21308059. The next prime is 21308081. The reversal of 21308069 is 96080312.

It can be written as a sum of positive squares in 4 ways, for example, as 940900 + 20367169 = 970^2 + 4513^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21308069 - 2⁸ = 21307813 is a prime.

It is a super-2 number, since 2×21308069² = 908067609017522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21308029) 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, 7772 + ... + 10149.

It is an arithmetic number, because the mean of its divisors is an integer number (2822715).

Almost surely, 2^21308069 is an apocalyptic number.

21308069 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21308069 is a deficient number, since it is larger than the sum of its proper divisors (1273651).

21308069 is a wasteful number, since it uses less digits than its factorization.

21308069 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17991.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 21308069 is about 4616.0663990025. The cubic root of 21308069 is about 277.2349833030.

The spelling of 21308069 in words is "twenty-one million, three hundred eight thousand, sixty-nine".