20231521 has 8 divisors (see below), whose sum is σ = 20827584. Its totient is φ = 19644240.

The previous prime is 20231507. The next prime is 20231527. The reversal of 20231521 is 12513202.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20231521 - 2¹⁵ = 20198753 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20231495 and 20231504.

It is not an unprimeable number, because it can be changed into a prime (20231527) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2631 + ... + 6883.

It is an arithmetic number, because the mean of its divisors is an integer number (2603448).

Almost surely, 2^20231521 is an apocalyptic number.

It is an amenable number.

20231521 is a deficient number, since it is larger than the sum of its proper divisors (596063).

20231521 is an equidigital number, since it uses as much as digits as its factorization.

20231521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4391.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 20231521 is about 4497.9463091504. The cubic root of 20231521 is about 272.4851536394.

Adding to 20231521 its reverse (12513202), we get a palindrome (32744723).

The spelling of 20231521 in words is "twenty million, two hundred thirty-one thousand, five hundred twenty-one".