21473545 has 24 divisors (see below), whose sum is σ = 27525960. Its totient is φ = 16070400.

The previous prime is 21473531. The next prime is 21473549. The reversal of 21473545 is 54537412.

It can be written as a sum of positive squares in 4 ways, for example, as 423801 + 21049744 = 651^2 + 4588^2 .

It is not a de Polignac number, because 21473545 - 2¹⁷ = 21342473 is a prime.

It is a super-2 number, since 2×21473545² = 922226269734050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21473549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 196951 + ... + 197059.

It is an arithmetic number, because the mean of its divisors is an integer number (1146915).

Almost surely, 2^21473545 is an apocalyptic number.

It is an amenable number.

21473545 is a deficient number, since it is larger than the sum of its proper divisors (6052415).

21473545 is a wasteful number, since it uses less digits than its factorization.

21473545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 217 (or 186 counting only the distinct ones).

The product of its digits is 16800, while the sum is 31.

The square root of 21473545 is about 4633.9556536506. The cubic root of 21473545 is about 277.9507918009.

The spelling of 21473545 in words is "twenty-one million, four hundred seventy-three thousand, five hundred forty-five".