21536473 has 16 divisors (see below), whose sum is σ = 25620480. Its totient is φ = 17712576.

The previous prime is 21536461. The next prime is 21536491. The reversal of 21536473 is 37463512.

It is not a de Polignac number, because 21536473 - 2¹⁷ = 21405401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21536453) 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 15 ways as a sum of consecutive naturals, for example, 56040 + ... + 56422.

It is an arithmetic number, because the mean of its divisors is an integer number (1601280).

Almost surely, 2^21536473 is an apocalyptic number.

It is an amenable number.

21536473 is a deficient number, since it is larger than the sum of its proper divisors (4084007).

21536473 is a wasteful number, since it uses less digits than its factorization.

21536473 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 696.

The product of its digits is 15120, while the sum is 31.

The square root of 21536473 is about 4640.7405659011. The cubic root of 21536473 is about 278.2220376458. Note that the first 3 decimals are identical.

Adding to 21536473 its reverse (37463512), we get a palindrome (58999985).

The spelling of 21536473 in words is "twenty-one million, five hundred thirty-six thousand, four hundred seventy-three".