21001000100031 has 24 divisors (see below), whose sum is σ = 34678801282944. Its totient is φ = 11996942527440.

The previous prime is 21001000099949. The next prime is 21001000100057. The reversal of 21001000100031 is 13000100010012.

It is not a de Polignac number, because 21001000100031 - 2⁷ = 21001000099903 is a prime.

It is a super-2 number, since 2×21001000100031² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21001000099986 and 21001000100022.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001000100081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 50192205 + ... + 50608886.

It is an arithmetic number, because the mean of its divisors is an integer number (1444950053456).

Almost surely, 2^{21001000100031} is an apocalyptic number.

21001000100031 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21001000100031 is a deficient number, since it is larger than the sum of its proper divisors (13677801182913).

21001000100031 is a wasteful number, since it uses less digits than its factorization.

21001000100031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100804411 (or 100804408 counting only the distinct ones).

The product of its (nonzero) digits is 6, while the sum is 9.

Adding to 21001000100031 its reverse (13000100010012), we get a palindrome (34001100110043).

The spelling of 21001000100031 in words is "twenty-one trillion, one billion, one hundred thousand, thirty-one".