21051043 has 4 divisors (see below), whose sum is σ = 22670368. Its totient is φ = 19431720.

The previous prime is 21051029. The next prime is 21051047. The reversal of 21051043 is 34015012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21051043 - 2⁵ = 21051011 is a prime.

It is a super-2 number, since 2×21051043² = 886292822775698, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21051047) 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, 809643 + ... + 809668.

It is an arithmetic number, because the mean of its divisors is an integer number (5667592).

Almost surely, 2^21051043 is an apocalyptic number.

21051043 is a deficient number, since it is larger than the sum of its proper divisors (1619325).

21051043 is a wasteful number, since it uses less digits than its factorization.

21051043 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1619324.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21051043 is about 4588.1415627681. The cubic root of 21051043 is about 276.1157665655.

Adding to 21051043 its reverse (34015012), we get a palindrome (55066055).

The spelling of 21051043 in words is "twenty-one million, fifty-one thousand, forty-three".