21999912 has 64 divisors (see below), whose sum is σ = 60480000. Its totient is φ = 6613440.

The previous prime is 21999911. The next prime is 21999917.

21999912 is nontrivially palindromic in base 10.

It is a super-3 number, since 3×21999912³ (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 (21999911) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 43839 + ... + 44337.

It is an arithmetic number, because the mean of its divisors is an integer number (945000).

Almost surely, 2^21999912 is an apocalyptic number.

21999912 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21999912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30240000).

21999912 is an abundant number, since it is smaller than the sum of its proper divisors (38480088).

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

21999912 is a wasteful number, since it uses less digits than its factorization.

21999912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 686 (or 682 counting only the distinct ones).

The product of its digits is 26244, while the sum is 42.

The square root of 21999912 is about 4690.4063789825. The cubic root of 21999912 is about 280.2035594598.

The spelling of 21999912 in words is "twenty-one million, nine hundred ninety-nine thousand, nine hundred twelve".