21487545 has 16 divisors (see below), whose sum is σ = 38200320. Its totient is φ = 11459952.

The previous prime is 21487519. The next prime is 21487547. The reversal of 21487545 is 54578412.

It is not a de Polignac number, because 21487545 - 2⁶ = 21487481 is a prime.

It is a super-3 number, since 3×21487545³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21487547) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 79449 + ... + 79718.

It is an arithmetic number, because the mean of its divisors is an integer number (2387520).

Almost surely, 2^21487545 is an apocalyptic number.

It is an amenable number.

21487545 is a deficient number, since it is larger than the sum of its proper divisors (16712775).

21487545 is a wasteful number, since it uses less digits than its factorization.

21487545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159181 (or 159175 counting only the distinct ones).

The product of its digits is 44800, while the sum is 36.

The square root of 21487545 is about 4635.4659959922. The cubic root of 21487545 is about 278.0111834088.

The spelling of 21487545 in words is "twenty-one million, four hundred eighty-seven thousand, five hundred forty-five".