21727540 has 24 divisors (see below), whose sum is σ = 46742472. Its totient is φ = 8478720.

The previous prime is 21727493. The next prime is 21727543. The reversal of 21727540 is 4572712.

It can be written as a sum of positive squares in 4 ways, for example, as 1710864 + 20016676 = 1308^2 + 4474^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21727499 and 21727508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21727543) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12429 + ... + 14068.

It is an arithmetic number, because the mean of its divisors is an integer number (1947603).

Almost surely, 2^21727540 is an apocalyptic number.

21727540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21727540 is an abundant number, since it is smaller than the sum of its proper divisors (25014932).

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

21727540 is a wasteful number, since it uses less digits than its factorization.

21727540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26547 (or 26545 counting only the distinct ones).

The product of its (nonzero) digits is 3920, while the sum is 28.

The square root of 21727540 is about 4661.2809398276. The cubic root of 21727540 is about 279.0423919518.

The spelling of 21727540 in words is "twenty-one million, seven hundred twenty-seven thousand, five hundred forty".