21523073 has 16 divisors (see below), whose sum is σ = 25909632. Its totient is φ = 17616000.

The previous prime is 21523069. The next prime is 21523093. The reversal of 21523073 is 37032512.

It is a cyclic number.

It is not a de Polignac number, because 21523073 - 2² = 21523069 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21523063) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4028 + ... + 7698.

It is an arithmetic number, because the mean of its divisors is an integer number (1619352).

Almost surely, 2^21523073 is an apocalyptic number.

It is an amenable number.

21523073 is a deficient number, since it is larger than the sum of its proper divisors (4386559).

21523073 is a wasteful number, since it uses less digits than its factorization.

21523073 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3736.

The product of its (nonzero) digits is 1260, while the sum is 23.

The square root of 21523073 is about 4639.2966061678. The cubic root of 21523073 is about 278.1643223954.

Adding to 21523073 its reverse (37032512), we get a palindrome (58555585).

It can be divided in two parts, 2152 and 3073, that added together give a palindrome (5225).

The spelling of 21523073 in words is "twenty-one million, five hundred twenty-three thousand, seventy-three".