21315573 has 12 divisors (see below), whose sum is σ = 31505760. Its totient is φ = 13879656.

The previous prime is 21315571. The next prime is 21315583. The reversal of 21315573 is 37551312.

It is not a de Polignac number, because 21315573 - 2¹ = 21315571 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21315571) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27153 + ... + 27926.

It is an arithmetic number, because the mean of its divisors is an integer number (2625480).

Almost surely, 2^21315573 is an apocalyptic number.

It is an amenable number.

21315573 is a deficient number, since it is larger than the sum of its proper divisors (10190187).

21315573 is a wasteful number, since it uses less digits than its factorization.

21315573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55128 (or 55125 counting only the distinct ones).

The product of its digits is 3150, while the sum is 27.

The square root of 21315573 is about 4616.8791407183. The cubic root of 21315573 is about 277.2675238264.

Adding to 21315573 its reverse (37551312), we get a palindrome (58866885).

The spelling of 21315573 in words is "twenty-one million, three hundred fifteen thousand, five hundred seventy-three".