16653721 has 8 divisors (see below), whose sum is σ = 19317440. Its totient is φ = 14061168.

The previous prime is 16653697. The next prime is 16653733. The reversal of 16653721 is 12735661.

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 16653721 - 2¹¹ = 16651673 is a prime.

It is not an unprimeable number, because it can be changed into a prime (16653751) 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, 17286 + ... + 18223.

It is an arithmetic number, because the mean of its divisors is an integer number (2414680).

Almost surely, 2^16653721 is an apocalyptic number.

It is an amenable number.

16653721 is a deficient number, since it is larger than the sum of its proper divisors (2663719).

16653721 is an equidigital number, since it uses as much as digits as its factorization.

16653721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35583.

The product of its digits is 7560, while the sum is 31.

The square root of 16653721 is about 4080.8970827503. The cubic root of 16653721 is about 255.3703244238.

The spelling of 16653721 in words is "sixteen million, six hundred fifty-three thousand, seven hundred twenty-one".