21920012 has 12 divisors (see below), whose sum is σ = 40028016. Its totient is φ = 10483440.

The previous prime is 21920011. The next prime is 21920023. The reversal of 21920012 is 21002912.

It is a super-4 number, since 4×21920012⁴ (a number of 30 digits) contains 4444 as substring.

It is not an unprimeable number, because it can be changed into a prime (21920011) 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, 119039 + ... + 119222.

It is an arithmetic number, because the mean of its divisors is an integer number (3335668).

Almost surely, 2^21920012 is an apocalyptic number.

It is an amenable number.

21920012 is a deficient number, since it is larger than the sum of its proper divisors (18108004).

21920012 is a wasteful number, since it uses less digits than its factorization.

21920012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 238288 (or 238286 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 21920012 is about 4681.8812458242. The cubic root of 21920012 is about 279.8639304847.

Adding to 21920012 its reverse (21002912), we get a palindrome (42922924).

The spelling of 21920012 in words is "twenty-one million, nine hundred twenty thousand, twelve".