21125006031 has 4 divisors (see below), whose sum is σ = 28166674712. Its totient is φ = 14083337352.

The previous prime is 21125006027. The next prime is 21125006047. The reversal of 21125006031 is 13060052112.

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

It is not a de Polignac number, because 21125006031 - 2² = 21125006027 is a prime.

It is a super-2 number, since 2×21125006031² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21125005989 and 21125006007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21125006051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3520834336 + ... + 3520834341.

It is an arithmetic number, because the mean of its divisors is an integer number (7041668678).

Almost surely, 2^21125006031 is an apocalyptic number.

21125006031 is a deficient number, since it is larger than the sum of its proper divisors (7041668681).

21125006031 is an equidigital number, since it uses as much as digits as its factorization.

21125006031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7041668680.

The product of its (nonzero) digits is 360, while the sum is 21.

Adding to 21125006031 its reverse (13060052112), we get a palindrome (34185058143).

The spelling of 21125006031 in words is "twenty-one billion, one hundred twenty-five million, six thousand, thirty-one".