21240232531 has 32 divisors (see below), whose sum is σ = 25924534272. Its totient is φ = 16987553280.

The previous prime is 21240232529. The next prime is 21240232547. The reversal of 21240232531 is 13523204212.

It is not a de Polignac number, because 21240232531 - 2¹ = 21240232529 is a prime.

It is a super-2 number, since 2×21240232531² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21240232496 and 21240232505.

It is not an unprimeable number, because it can be changed into a prime (21240202531) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 7903470 + ... + 7906156.

It is an arithmetic number, because the mean of its divisors is an integer number (810141696).

Almost surely, 2^21240232531 is an apocalyptic number.

21240232531 is a deficient number, since it is larger than the sum of its proper divisors (4684301741).

21240232531 is a wasteful number, since it uses less digits than its factorization.

21240232531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3259.

The product of its (nonzero) digits is 2880, while the sum is 25.

Adding to 21240232531 its reverse (13523204212), we get a palindrome (34763436743).

The spelling of 21240232531 in words is "twenty-one billion, two hundred forty million, two hundred thirty-two thousand, five hundred thirty-one".