21575540 has 24 divisors (see below), whose sum is σ = 51781632. Its totient is φ = 7397280.

The previous prime is 21575537. The next prime is 21575549. The reversal of 21575540 is 4557512.

It is a Smith number, since the sum of its digits (29) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21575549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76916 + ... + 77195.

It is an arithmetic number, because the mean of its divisors is an integer number (2157568).

Almost surely, 2^21575540 is an apocalyptic number.

21575540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21575540 is an abundant number, since it is smaller than the sum of its proper divisors (30206092).

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

21575540 is a wasteful number, since it uses less digits than its factorization.

21575540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154127 (or 154125 counting only the distinct ones).

The product of its (nonzero) digits is 7000, while the sum is 29.

The square root of 21575540 is about 4644.9477930328. The cubic root of 21575540 is about 278.3901669194.

The spelling of 21575540 in words is "twenty-one million, five hundred seventy-five thousand, five hundred forty".