21131431231021 has 32 divisors (see below), whose sum is σ = 22221953424000. Its totient is φ = 20068286499072.

The previous prime is 21131431231013. The next prime is 21131431231067. The reversal of 21131431231021 is 12013213413112.

It is a cyclic number.

It is not a de Polignac number, because 21131431231021 - 2³ = 21131431231013 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131431234021) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 248946375 + ... + 249031243.

It is an arithmetic number, because the mean of its divisors is an integer number (694436044500).

Almost surely, 2^{21131431231021} is an apocalyptic number.

It is an amenable number.

21131431231021 is a deficient number, since it is larger than the sum of its proper divisors (1090522192979).

21131431231021 is a wasteful number, since it uses less digits than its factorization.

21131431231021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85581.

The product of its (nonzero) digits is 864, while the sum is 25.

Adding to 21131431231021 its reverse (12013213413112), we get a palindrome (33144644644133).

The spelling of 21131431231021 in words is "twenty-one trillion, one hundred thirty-one billion, four hundred thirty-one million, two hundred thirty-one thousand, twenty-one".