21481812 has 72 divisors (see below), whose sum is σ = 62741952. Its totient is φ = 6124800.

The previous prime is 21481807. The next prime is 21481847. The reversal of 21481812 is 21818412.

It is a super-2 number, since 2×21481812² = 922936493606688, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5137 + ... + 8327.

It is an arithmetic number, because the mean of its divisors is an integer number (871416).

Almost surely, 2^21481812 is an apocalyptic number.

21481812 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 21481812, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31370976).

21481812 is an abundant number, since it is smaller than the sum of its proper divisors (41260140).

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

21481812 is a wasteful number, since it uses less digits than its factorization.

21481812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3229 (or 3224 counting only the distinct ones).

The product of its digits is 1024, while the sum is 27.

The square root of 21481812 is about 4634.8475703091. The cubic root of 21481812 is about 277.9864562178.

The spelling of 21481812 in words is "twenty-one million, four hundred eighty-one thousand, eight hundred twelve".