21200100031 has 4 divisors (see below), whose sum is σ = 23127381864. Its totient is φ = 19272818200.

The previous prime is 21200100029. The next prime is 21200100043. The reversal of 21200100031 is 13000100212.

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 21200100031 - 2¹ = 21200100029 is a prime.

It is a super-2 number, since 2×21200100031² (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 = 21200099990 and 21200100017.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21200100931) 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, 963640900 + ... + 963640921.

It is an arithmetic number, because the mean of its divisors is an integer number (5781845466).

Almost surely, 2^21200100031 is an apocalyptic number.

21200100031 is a deficient number, since it is larger than the sum of its proper divisors (1927281833).

21200100031 is a wasteful number, since it uses less digits than its factorization.

21200100031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1927281832.

The product of its (nonzero) digits is 12, while the sum is 10.

Adding to 21200100031 its reverse (13000100212), we get a palindrome (34200200243).

The spelling of 21200100031 in words is "twenty-one billion, two hundred million, one hundred thousand, thirty-one".