21473538 has 16 divisors (see below), whose sum is σ = 43001760. Its totient is φ = 7148736.

The previous prime is 21473531. The next prime is 21473549. The reversal of 21473538 is 83537412.

It is a super-2 number, since 2×21473538² = 922225668474888, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21473499 and 21473508.

It is not an unprimeable number, because it can be changed into a prime (21473531) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4281 + ... + 7827.

It is an arithmetic number, because the mean of its divisors is an integer number (2687610).

Almost surely, 2^21473538 is an apocalyptic number.

21473538 is an abundant number, since it is smaller than the sum of its proper divisors (21528222).

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

21473538 is a wasteful number, since it uses less digits than its factorization.

21473538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4561.

The product of its digits is 20160, while the sum is 33.

The square root of 21473538 is about 4633.9548983563. The cubic root of 21473538 is about 277.9507615986.

The spelling of 21473538 in words is "twenty-one million, four hundred seventy-three thousand, five hundred thirty-eight".