16231721 has 8 divisors (see below), whose sum is σ = 18477504. Its totient is φ = 14114320.

The previous prime is 16231717. The next prime is 16231723. The reversal of 16231721 is 12713261.

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

It is not a de Polignac number, because 16231721 - 2² = 16231717 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16231723) 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, 31826 + ... + 32331.

It is an arithmetic number, because the mean of its divisors is an integer number (2309688).

Almost surely, 2^16231721 is an apocalyptic number.

16231721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

16231721 is a deficient number, since it is larger than the sum of its proper divisors (2245783).

16231721 is a wasteful number, since it uses less digits than its factorization.

16231721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64191.

The product of its digits is 504, while the sum is 23.

The square root of 16231721 is about 4028.8610052967. The cubic root of 16231721 is about 253.1948433188.

Adding to 16231721 its reverse (12713261), we get a palindrome (28944982).

The spelling of 16231721 in words is "sixteen million, two hundred thirty-one thousand, seven hundred twenty-one".