21499540 has 12 divisors (see below), whose sum is σ = 45149076. Its totient is φ = 8599808.

The previous prime is 21499501. The next prime is 21499561. The reversal of 21499540 is 4599412.

It can be written as a sum of positive squares in 2 ways, for example, as 16499844 + 4999696 = 4062^2 + 2236^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21499496 and 21499505.

It is a congruent number.

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, 537469 + ... + 537508.

It is an arithmetic number, because the mean of its divisors is an integer number (3762423).

Almost surely, 2^21499540 is an apocalyptic number.

21499540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21499540 is an abundant number, since it is smaller than the sum of its proper divisors (23649536).

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

21499540 is a wasteful number, since it uses less digits than its factorization.

21499540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1074986 (or 1074984 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 34.

The square root of 21499540 is about 4636.7596444069. The cubic root of 21499540 is about 278.0629052135.

The spelling of 21499540 in words is "twenty-one million, four hundred ninety-nine thousand, five hundred forty".