21131254031 has 4 divisors (see below), whose sum is σ = 22374268992. Its totient is φ = 19888239072.

The previous prime is 21131254007. The next prime is 21131254043. The reversal of 21131254031 is 13045213112.

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

It is a de Polignac number, because none of the positive numbers 2^k-21131254031 is a prime.

It is a super-2 number, since 2×21131254031² (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 = 21131253988 and 21131254006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131254051) 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, 621507455 + ... + 621507488.

It is an arithmetic number, because the mean of its divisors is an integer number (5593567248).

Almost surely, 2^21131254031 is an apocalyptic number.

21131254031 is a deficient number, since it is larger than the sum of its proper divisors (1243014961).

21131254031 is a wasteful number, since it uses less digits than its factorization.

21131254031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1243014960.

The product of its (nonzero) digits is 720, while the sum is 23.

Adding to 21131254031 its reverse (13045213112), we get a palindrome (34176467143).

The spelling of 21131254031 in words is "twenty-one billion, one hundred thirty-one million, two hundred fifty-four thousand, thirty-one".