21401331231 has 64 divisors (see below), whose sum is σ = 34612531200. Its totient is φ = 11503220736.

The previous prime is 21401331227. The next prime is 21401331239. The reversal of 21401331231 is 13213310412.

It is not a de Polignac number, because 21401331231 - 2² = 21401331227 is a prime.

It is a super-2 number, since 2×21401331231² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a junction number, because it is equal to n+sod(n) for n = 21401331198 and 21401331207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21401331239) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 6667555 + ... + 6670763.

It is an arithmetic number, because the mean of its divisors is an integer number (540820800).

Almost surely, 2^21401331231 is an apocalyptic number.

21401331231 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21401331231 is a deficient number, since it is larger than the sum of its proper divisors (13211199969).

21401331231 is a wasteful number, since it uses less digits than its factorization.

21401331231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3528.

The product of its (nonzero) digits is 432, while the sum is 21.

Adding to 21401331231 its reverse (13213310412), we get a palindrome (34614641643).

The spelling of 21401331231 in words is "twenty-one billion, four hundred one million, three hundred thirty-one thousand, two hundred thirty-one".