21023523 has 16 divisors (see below), whose sum is σ = 31810560. Its totient is φ = 13716648.

The previous prime is 21023503. The next prime is 21023531. The reversal of 21023523 is 32532012.

It is not a de Polignac number, because 21023523 - 2⁶ = 21023459 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21023496 and 21023505.

It is not an unprimeable number, because it can be changed into a prime (21023503) 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, 7015 + ... + 9552.

It is an arithmetic number, because the mean of its divisors is an integer number (1988160).

Almost surely, 2^21023523 is an apocalyptic number.

21023523 is a deficient number, since it is larger than the sum of its proper divisors (10787037).

21023523 is a wasteful number, since it uses less digits than its factorization.

21023523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16623 (or 16617 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 18.

The square root of 21023523 is about 4585.1415463429. The cubic root of 21023523 is about 275.9953921726.

Adding to 21023523 its reverse (32532012), we get a palindrome (53555535).

It can be divided in two parts, 2102 and 3523, that added together give a square (5625 = 75²).

The spelling of 21023523 in words is "twenty-one million, twenty-three thousand, five hundred twenty-three".