21111001031 has 4 divisors (see below), whose sum is σ = 21113241864. Its totient is φ = 21108760200.

The previous prime is 21111000997. The next prime is 21111001057. The reversal of 21111001031 is 13010011112.

It is a happy number.

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 21111001031 - 2¹⁰ = 21111000007 is a prime.

It is a super-2 number, since 2×21111001031² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111006031) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1106225 + ... + 1125146.

It is an arithmetic number, because the mean of its divisors is an integer number (5278310466).

Almost surely, 2^21111001031 is an apocalyptic number.

21111001031 is a deficient number, since it is larger than the sum of its proper divisors (2240833).

21111001031 is an equidigital number, since it uses as much as digits as its factorization.

21111001031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2240832.

The product of its (nonzero) digits is 6, while the sum is 11.

Adding to 21111001031 its reverse (13010011112), we get a palindrome (34121012143).

The spelling of 21111001031 in words is "twenty-one billion, one hundred eleven million, one thousand, thirty-one".