21531212441 has 8 divisors (see below), whose sum is σ = 21991409280. Its totient is φ = 21071102608.

The previous prime is 21531212413. The next prime is 21531212449. The reversal of 21531212441 is 14421213512.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21531212441 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21531212441.

It is not an unprimeable number, because it can be changed into a prime (21531212449) 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, 832655 + ... + 858123.

It is an arithmetic number, because the mean of its divisors is an integer number (2748926160).

Almost surely, 2^21531212441 is an apocalyptic number.

It is an amenable number.

21531212441 is a deficient number, since it is larger than the sum of its proper divisors (460196839).

21531212441 is a wasteful number, since it uses less digits than its factorization.

21531212441 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43503.

The product of its digits is 1920, while the sum is 26.

Adding to 21531212441 its reverse (14421213512), we get a palindrome (35952425953).

The spelling of 21531212441 in words is "twenty-one billion, five hundred thirty-one million, two hundred twelve thousand, four hundred forty-one".