21021219 has 6 divisors (see below), whose sum is σ = 30363996. Its totient is φ = 14014140.

The previous prime is 21021181. The next prime is 21021229. The reversal of 21021219 is 91212012.

It is not a de Polignac number, because 21021219 - 2⁸ = 21020963 is a prime.

It is a super-3 number, since 3×21021219³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (21021229) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1167837 + ... + 1167854.

It is an arithmetic number, because the mean of its divisors is an integer number (5060666).

Almost surely, 2^21021219 is an apocalyptic number.

21021219 is a deficient number, since it is larger than the sum of its proper divisors (9342777).

21021219 is a wasteful number, since it uses less digits than its factorization.

21021219 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2335697 (or 2335694 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 21021219 is about 4584.8902931259. The cubic root of 21021219 is about 275.9853095521.

It can be divided in two parts, 2102 and 1219, that added together give a triangular number (3321 = T₈₁).

The spelling of 21021219 in words is "twenty-one million, twenty-one thousand, two hundred nineteen".