21540826 has 8 divisors (see below), whose sum is σ = 33099444. Its totient is φ = 10507680.

The previous prime is 21540817. The next prime is 21540833. The reversal of 21540826 is 62804512.

It can be written as a sum of positive squares in 2 ways, for example, as 16410601 + 5130225 = 4051^2 + 2265^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 21540794 and 21540803.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 131265 + ... + 131428.

Almost surely, 2^21540826 is an apocalyptic number.

21540826 is a deficient number, since it is larger than the sum of its proper divisors (11558618).

21540826 is a wasteful number, since it uses less digits than its factorization.

21540826 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262736.

The product of its (nonzero) digits is 3840, while the sum is 28.

The square root of 21540826 is about 4641.2095406262. The cubic root of 21540826 is about 278.2407813361.

It can be divided in two parts, 21540 and 826, that added together give a triangular number (22366 = T₂₁₁).

The spelling of 21540826 in words is "twenty-one million, five hundred forty thousand, eight hundred twenty-six".