20233721 has 8 divisors (see below), whose sum is σ = 21166080. Its totient is φ = 19342356.

The previous prime is 20233691. The next prime is 20233739. The reversal of 20233721 is 12733202.

It is not a de Polignac number, because 20233721 - 2¹⁸ = 19971577 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20233693 and 20233702.

It is not an unprimeable number, because it can be changed into a prime (20233771) 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, 11336 + ... + 12998.

It is an arithmetic number, because the mean of its divisors is an integer number (2645760).

Almost surely, 2^20233721 is an apocalyptic number.

It is an amenable number.

20233721 is a deficient number, since it is larger than the sum of its proper divisors (932359).

20233721 is an frugal number, since it uses more digits than its factorization.

20233721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1732 (or 1686 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 20.

The square root of 20233721 is about 4498.1908585564. The cubic root of 20233721 is about 272.4950300696.

Adding to 20233721 its reverse (12733202), we get a palindrome (32966923).

The spelling of 20233721 in words is "twenty million, two hundred thirty-three thousand, seven hundred twenty-one".