21531232445 has 16 divisors (see below), whose sum is σ = 27742652928. Its totient is φ = 15983412480.

The previous prime is 21531232423. The next prime is 21531232447. The reversal of 21531232445 is 54423213512.

It is not a de Polignac number, because 21531232445 - 2¹⁸ = 21530970301 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531232447) 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, 1777829 + ... + 1789898.

It is an arithmetic number, because the mean of its divisors is an integer number (1733915808).

Almost surely, 2^21531232445 is an apocalyptic number.

It is an amenable number.

21531232445 is a deficient number, since it is larger than the sum of its proper divisors (6211420483).

21531232445 is a wasteful number, since it uses less digits than its factorization.

21531232445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3567820.

The product of its digits is 28800, while the sum is 32.

Adding to 21531232445 its reverse (54423213512), we get a palindrome (75954445957).

The spelling of 21531232445 in words is "twenty-one billion, five hundred thirty-one million, two hundred thirty-two thousand, four hundred forty-five".