21212004 has 24 divisors (see below), whose sum is σ = 53994528. Its totient is φ = 6427840.

The previous prime is 21211997. The next prime is 21212017. The reversal of 21212004 is 40021212.

It is a super-2 number, since 2×21212004² = 899898227392032, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 80217 + ... + 80480.

It is an arithmetic number, because the mean of its divisors is an integer number (2249772).

Almost surely, 2^21212004 is an apocalyptic number.

It is an amenable number.

21212004 is an abundant number, since it is smaller than the sum of its proper divisors (32782524).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21212004 is a wasteful number, since it uses less digits than its factorization.

21212004 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160715 (or 160713 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 12.

The square root of 21212004 is about 4605.6491399150. The cubic root of 21212004 is about 276.8177281850.

Adding to 21212004 its reverse (40021212), we get a palindrome (61233216).

The spelling of 21212004 in words is "twenty-one million, two hundred twelve thousand, four".