21155043 has 16 divisors (see below), whose sum is σ = 34716416. Its totient is φ = 11158560.

The previous prime is 21155041. The next prime is 21155053. The reversal of 21155043 is 34055112.

It is not a de Polignac number, because 21155043 - 2¹ = 21155041 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21155041) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38473 + ... + 39018.

It is an arithmetic number, because the mean of its divisors is an integer number (2169776).

Almost surely, 2^21155043 is an apocalyptic number.

21155043 is a deficient number, since it is larger than the sum of its proper divisors (13561373).

21155043 is a wasteful number, since it uses less digits than its factorization.

21155043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77514.

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 21155043 is about 4599.4611640930. The cubic root of 21155043 is about 276.5697247498.

The spelling of 21155043 in words is "twenty-one million, one hundred fifty-five thousand, forty-three".