21123042011 has 16 divisors (see below), whose sum is σ = 23161593600. Its totient is φ = 19174407168.

The previous prime is 21123041993. The next prime is 21123042019. The reversal of 21123042011 is 11024032112.

It is not a de Polignac number, because 21123042011 - 2¹⁰ = 21123040987 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21123042019) 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, 447350 + ... + 492308.

It is an arithmetic number, because the mean of its divisors is an integer number (1447599600).

Almost surely, 2^21123042011 is an apocalyptic number.

21123042011 is a deficient number, since it is larger than the sum of its proper divisors (2038551589).

21123042011 is a wasteful number, since it uses less digits than its factorization.

21123042011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45958.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21123042011 its reverse (11024032112), we get a palindrome (32147074123).

The spelling of 21123042011 in words is "twenty-one billion, one hundred twenty-three million, forty-two thousand, eleven".