21531204523412 has 24 divisors (see below), whose sum is σ = 37745419884480. Its totient is φ = 10746804358080.

The previous prime is 21531204523267. The next prime is 21531204523417. The reversal of 21531204523412 is 21432540213512.

It is a super-2 number, since 2×21531204523412² (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 (21531204523417) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15005639 + ... + 16377777.

It is an arithmetic number, because the mean of its divisors is an integer number (1572725828520).

Almost surely, 2^{21531204523412} is an apocalyptic number.

It is an amenable number.

21531204523412 is a deficient number, since it is larger than the sum of its proper divisors (16214215361068).

21531204523412 is a wasteful number, since it uses less digits than its factorization.

21531204523412 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1378991 (or 1378989 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 35.

Adding to 21531204523412 its reverse (21432540213512), we get a palindrome (42963744736924).

The spelling of 21531204523412 in words is "twenty-one trillion, five hundred thirty-one billion, two hundred four million, five hundred twenty-three thousand, four hundred twelve".