21523473 has 12 divisors (see below), whose sum is σ = 31131828. Its totient is φ = 14329440.

The previous prime is 21523433. The next prime is 21523499. The reversal of 21523473 is 37432512.

It can be written as a sum of positive squares in 2 ways, for example, as 10712529 + 10810944 = 3273^2 + 3288^2 .

It is not a de Polignac number, because 21523473 - 2⁹ = 21522961 is a prime.

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (21523433) 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, 8983 + ... + 11123.

It is an arithmetic number, because the mean of its divisors is an integer number (2594319).

Almost surely, 2^21523473 is an apocalyptic number.

It is an amenable number.

21523473 is a deficient number, since it is larger than the sum of its proper divisors (9608355).

21523473 is a wasteful number, since it uses less digits than its factorization.

21523473 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3264 (or 3261 counting only the distinct ones).

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

The square root of 21523473 is about 4639.3397159510. The cubic root of 21523473 is about 278.1660455855.

Adding to 21523473 its reverse (37432512), we get a palindrome (58955985).

It can be divided in two parts, 2152 and 3473, that added together give a square (5625 = 75²).

The spelling of 21523473 in words is "twenty-one million, five hundred twenty-three thousand, four hundred seventy-three".