16721801 has 4 divisors (see below), whose sum is σ = 17077632. Its totient is φ = 16365972.

The previous prime is 16721773. The next prime is 16721819. The reversal of 16721801 is 10812761.

16721801 = 89² + 90² + ... + 370².

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 10812761 = 257 ⋅42073.

It is a cyclic number.

It is not a de Polignac number, because 16721801 - 2⁶ = 16721737 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (16721821) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 177845 + ... + 177938.

It is an arithmetic number, because the mean of its divisors is an integer number (4269408).

Almost surely, 2^16721801 is an apocalyptic number.

It is an amenable number.

16721801 is a deficient number, since it is larger than the sum of its proper divisors (355831).

16721801 is an equidigital number, since it uses as much as digits as its factorization.

16721801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 355830.

The product of its (nonzero) digits is 672, while the sum is 26.

The square root of 16721801 is about 4089.2298785957. The cubic root of 16721801 is about 255.7178338422.

The spelling of 16721801 in words is "sixteen million, seven hundred twenty-one thousand, eight hundred one".