21451131564 has 24 divisors (see below), whose sum is σ = 50203866048. Its totient is φ = 7128773520.

The previous prime is 21451131563. The next prime is 21451131587. The reversal of 21451131564 is 46513115412.

It is not an unprimeable number, because it can be changed into a prime (21451131563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2696322 + ... + 2704265.

It is an arithmetic number, because the mean of its divisors is an integer number (2091827752).

Almost surely, 2^21451131564 is an apocalyptic number.

It is an amenable number.

21451131564 is an abundant number, since it is smaller than the sum of its proper divisors (28752734484).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21451131564 is a wasteful number, since it uses less digits than its factorization.

21451131564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5400925 (or 5400923 counting only the distinct ones).

The product of its digits is 14400, while the sum is 33.

Adding to 21451131564 its reverse (46513115412), we get a palindrome (67964246976).

The spelling of 21451131564 in words is "twenty-one billion, four hundred fifty-one million, one hundred thirty-one thousand, five hundred sixty-four".