21120540 has 48 divisors (see below), whose sum is σ = 67587072. Its totient is φ = 4827456.

The previous prime is 21120523. The next prime is 21120551. The reversal of 21120540 is 4502112.

It is a Harshad number since it is a multiple of its sum of digits (15).

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, 24724 + ... + 25563.

It is an arithmetic number, because the mean of its divisors is an integer number (1408064).

Almost surely, 2^21120540 is an apocalyptic number.

21120540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21120540 is an abundant number, since it is smaller than the sum of its proper divisors (46466532).

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

21120540 is a wasteful number, since it uses less digits than its factorization.

21120540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50306 (or 50304 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 15.

The square root of 21120540 is about 4595.7088680638. The cubic root of 21120540 is about 276.4192850065.

Adding to 21120540 its reverse (4502112), we get a palindrome (25622652).

The spelling of 21120540 in words is "twenty-one million, one hundred twenty thousand, five hundred forty".