21016554 has 32 divisors (see below), whose sum is σ = 45898944. Its totient is φ = 6376320.

The previous prime is 21016547. The next prime is 21016577. The reversal of 21016554 is 45561012.

It is a zygodrome in base 4.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3849 + ... + 7539.

It is an arithmetic number, because the mean of its divisors is an integer number (1434342).

Almost surely, 2^21016554 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21016554, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22949472).

21016554 is an abundant number, since it is smaller than the sum of its proper divisors (24882390).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21016554 is a wasteful number, since it uses less digits than its factorization.

21016554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3782.

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 21016554 is about 4584.3815286252. The cubic root of 21016554 is about 275.9648926150.

Adding to 21016554 its reverse (45561012), we get a palindrome (66577566).

The spelling of 21016554 in words is "twenty-one million, sixteen thousand, five hundred fifty-four".