21531315044 has 12 divisors (see below), whose sum is σ = 37693719168. Its totient is φ = 10761681000.

The previous prime is 21531315041. The next prime is 21531315053. The reversal of 21531315044 is 44051313512.

It is a junction number, because it is equal to n+sod(n) for n = 21531314998 and 21531315016.

It is not an unprimeable number, because it can be changed into a prime (21531315041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 981932 + ... + 1003619.

It is an arithmetic number, because the mean of its divisors is an integer number (3141143264).

Almost surely, 2^21531315044 is an apocalyptic number.

It is an amenable number.

21531315044 is a deficient number, since it is larger than the sum of its proper divisors (16162404124).

21531315044 is a wasteful number, since it uses less digits than its factorization.

21531315044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1988266 (or 1988264 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 29.

Adding to 21531315044 its reverse (44051313512), we get a palindrome (65582628556).

The spelling of 21531315044 in words is "twenty-one billion, five hundred thirty-one million, three hundred fifteen thousand, forty-four".