21531071752431 has 16 divisors (see below), whose sum is σ = 28989092580864. Its totient is φ = 14213571279264.

The previous prime is 21531071752423. The next prime is 21531071752453. The reversal of 21531071752431 is 13425717013512.

It is not a de Polignac number, because 21531071752431 - 2³ = 21531071752423 is a prime.

It is a super-2 number, since 2×21531071752431² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531071752471) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1210870 + ... + 6672956.

It is an arithmetic number, because the mean of its divisors is an integer number (1811818286304).

Almost surely, 2^{21531071752431} is an apocalyptic number.

21531071752431 is a deficient number, since it is larger than the sum of its proper divisors (7458020828433).

21531071752431 is a wasteful number, since it uses less digits than its factorization.

21531071752431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5474950.

The product of its (nonzero) digits is 176400, while the sum is 42.

Adding to 21531071752431 its reverse (13425717013512), we get a palindrome (34956788765943).

The spelling of 21531071752431 in words is "twenty-one trillion, five hundred thirty-one billion, seventy-one million, seven hundred fifty-two thousand, four hundred thirty-one".