21821069 has 4 divisors (see below), whose sum is σ = 22128480. Its totient is φ = 21513660.

The previous prime is 21821039. The next prime is 21821071. The reversal of 21821069 is 96012812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21821069 is a prime.

It is a super-2 number, since 2×21821069² = 952318104605522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21821039) 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, 153599 + ... + 153740.

It is an arithmetic number, because the mean of its divisors is an integer number (5532120).

Almost surely, 2^21821069 is an apocalyptic number.

It is an amenable number.

21821069 is a deficient number, since it is larger than the sum of its proper divisors (307411).

21821069 is an equidigital number, since it uses as much as digits as its factorization.

21821069 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 307410.

The product of its (nonzero) digits is 1728, while the sum is 29.

The square root of 21821069 is about 4671.3027090952. The cubic root of 21821069 is about 279.4422101392.

The spelling of 21821069 in words is "twenty-one million, eight hundred twenty-one thousand, sixty-nine".