21368540 has 48 divisors (see below), whose sum is σ = 48172320. Its totient is φ = 7937280.

The previous prime is 21368539. The next prime is 21368569. The reversal of 21368540 is 4586312.

It is a super-2 number, since 2×21368540² = 913229003463200, 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 15 ways as a sum of consecutive naturals, for example, 19610 + ... + 20670.

It is an arithmetic number, because the mean of its divisors is an integer number (1003590).

Almost surely, 2^21368540 is an apocalyptic number.

21368540 is a gapful number since it is divisible by the number (20) 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 21368540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24086160).

21368540 is an abundant number, since it is smaller than the sum of its proper divisors (26803780).

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

21368540 is a wasteful number, since it uses less digits than its factorization.

21368540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1142 (or 1140 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 29.

The square root of 21368540 is about 4622.6118158461. The cubic root of 21368540 is about 277.4969942590.

The spelling of 21368540 in words is "twenty-one million, three hundred sixty-eight thousand, five hundred forty".