21045156 has 96 divisors (see below), whose sum is σ = 57200640. Its totient is φ = 5961600.

The previous prime is 21045151. The next prime is 21045197. The reversal of 21045156 is 65154012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21045151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 151335 + ... + 151473.

It is an arithmetic number, because the mean of its divisors is an integer number (595840).

Almost surely, 2^21045156 is an apocalyptic number.

It is a pronic number, being equal to 4587×4588.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21045156, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28600320).

21045156 is an abundant number, since it is smaller than the sum of its proper divisors (36155484).

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

21045156 is a wasteful number, since it uses less digits than its factorization.

21045156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 225 (or 223 counting only the distinct ones).

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

The square root of 21045156 is about 4587.4999727520. The cubic root of 21045156 is about 276.0900252429.

Adding to 21045156 its reverse (65154012), we get a palindrome (86199168).

It can be divided in two parts, 2104 and 5156, that added together give a triangular number (7260 = T₁₂₀).

The spelling of 21045156 in words is "twenty-one million, forty-five thousand, one hundred fifty-six".