21156073 has 4 divisors (see below), whose sum is σ = 21171328. Its totient is φ = 21140820.

The previous prime is 21156071. The next prime is 21156077. The reversal of 21156073 is 37065112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21156073 - 2¹ = 21156071 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21156071) 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 3 ways as a sum of consecutive naturals, for example, 5313 + ... + 8398.

It is an arithmetic number, because the mean of its divisors is an integer number (5292832).

Almost surely, 2^21156073 is an apocalyptic number.

It is an amenable number.

21156073 is a deficient number, since it is larger than the sum of its proper divisors (15255).

21156073 is a wasteful number, since it uses less digits than its factorization.

21156073 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15254.

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 21156073 is about 4599.5731323678. The cubic root of 21156073 is about 276.5742132335.

The spelling of 21156073 in words is "twenty-one million, one hundred fifty-six thousand, seventy-three".