21532473 has 14 divisors (see below), whose sum is σ = 32285034. Its totient is φ = 14354496.

The previous prime is 21532417. The next prime is 21532499. The reversal of 21532473 is 37423512.

It can be written as a sum of positive squares in only one way, i.e., 11209104 + 10323369 = 3348^2 + 3213^2 .

It is not a de Polignac number, because 21532473 - 2¹³ = 21524281 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (21532403) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 14040 + ... + 15497.

Almost surely, 2^21532473 is an apocalyptic number.

It is an amenable number.

21532473 is a deficient number, since it is larger than the sum of its proper divisors (10752561).

21532473 is an frugal number, since it uses more digits than its factorization.

21532473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29555 (or 29540 counting only the distinct ones).

The product of its digits is 5040, while the sum is 27.

The square root of 21532473 is about 4640.3095801897. The cubic root of 21532473 is about 278.2048117200.

Adding to 21532473 its reverse (37423512), we get a palindrome (58955985).

The spelling of 21532473 in words is "twenty-one million, five hundred thirty-two thousand, four hundred seventy-three".