21122540 has 24 divisors (see below), whose sum is σ = 44473632. Its totient is φ = 8426880.

The previous prime is 21122473. The next prime is 21122561. The reversal of 21122540 is 4522112.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7985 + ... + 10295.

It is an arithmetic number, because the mean of its divisors is an integer number (1853068).

Almost surely, 2^21122540 is an apocalyptic number.

21122540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21122540 is an abundant number, since it is smaller than the sum of its proper divisors (23351092).

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

21122540 is a wasteful number, since it uses less digits than its factorization.

21122540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2777 (or 2775 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21122540 is about 4595.9264572010. The cubic root of 21122540 is about 276.4280098642.

Adding to 21122540 its reverse (4522112), we get a palindrome (25644652).

The spelling of 21122540 in words is "twenty-one million, one hundred twenty-two thousand, five hundred forty".