16721387 has 8 divisors (see below), whose sum is σ = 18637200. Its totient is φ = 14909184.

The previous prime is 16721357. The next prime is 16721407. The reversal of 16721387 is 78312761.

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 16721387 - 2¹⁶ = 16655851 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16721347) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25562 + ... + 26207.

It is an arithmetic number, because the mean of its divisors is an integer number (2329650).

Almost surely, 2^16721387 is an apocalyptic number.

16721387 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

16721387 is a deficient number, since it is larger than the sum of its proper divisors (1915813).

16721387 is a wasteful number, since it uses less digits than its factorization.

16721387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51805.

The product of its digits is 14112, while the sum is 35.

The square root of 16721387 is about 4089.1792575039. The cubic root of 16721387 is about 255.7157234623.

The spelling of 16721387 in words is "sixteen million, seven hundred twenty-one thousand, three hundred eighty-seven".