21020069 has 8 divisors (see below), whose sum is σ = 24513600. Its totient is φ = 18016908.

The previous prime is 21020059. The next prime is 21020081. The reversal of 21020069 is 96002012.

It is not a de Polignac number, because 21020069 - 2⁴ = 21020053 is a prime.

It is a super-2 number, since 2×21020069² = 883686601529522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21020069.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020029) 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, 30299 + ... + 30984.

It is an arithmetic number, because the mean of its divisors is an integer number (3064200).

Almost surely, 2^21020069 is an apocalyptic number.

It is an amenable number.

21020069 is a deficient number, since it is larger than the sum of its proper divisors (3493531).

21020069 is an frugal number, since it uses more digits than its factorization.

21020069 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61304 (or 61290 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 21020069 is about 4584.7648794676. The cubic root of 21020069 is about 275.9802767184.

The spelling of 21020069 in words is "twenty-one million, twenty thousand, sixty-nine".