21156045 has 16 divisors (see below), whose sum is σ = 34765440. Its totient is φ = 10977984.

The previous prime is 21156029. The next prime is 21156049. The reversal of 21156045 is 54065112.

It is not a de Polignac number, because 21156045 - 2⁴ = 21156029 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21156049) 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 15 ways as a sum of consecutive naturals, for example, 18505 + ... + 19614.

It is an arithmetic number, because the mean of its divisors is an integer number (2172840).

Almost surely, 2^21156045 is an apocalyptic number.

It is an amenable number.

21156045 is a deficient number, since it is larger than the sum of its proper divisors (13609395).

21156045 is a wasteful number, since it uses less digits than its factorization.

21156045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38164.

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

The square root of 21156045 is about 4599.5700886061. The cubic root of 21156045 is about 276.5740912184.

The spelling of 21156045 in words is "twenty-one million, one hundred fifty-six thousand, forty-five".