16621420721 has 8 divisors (see below), whose sum is σ = 16721003520. Its totient is φ = 16521913008.

The previous prime is 16621420687. The next prime is 16621420729. The reversal of 16621420721 is 12702412661.

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 16621420721 - 2¹⁸ = 16621158577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16621420729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 461840 + ... + 496526.

It is an arithmetic number, because the mean of its divisors is an integer number (2090125440).

Almost surely, 2^16621420721 is an apocalyptic number.

It is an amenable number.

16621420721 is a deficient number, since it is larger than the sum of its proper divisors (99582799).

16621420721 is a wasteful number, since it uses less digits than its factorization.

16621420721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37543.

The product of its (nonzero) digits is 8064, while the sum is 32.

The spelling of 16621420721 in words is "sixteen billion, six hundred twenty-one million, four hundred twenty thousand, seven hundred twenty-one".