21125411540 has 24 divisors (see below), whose sum is σ = 45445399272. Its totient is φ = 8244062720.

The previous prime is 21125411533. The next prime is 21125411569. The reversal of 21125411540 is 4511452112.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 615734596 + 20509676944 = 24814^2 + 143212^2 .

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 12880529 + ... + 12882168.

It is an arithmetic number, because the mean of its divisors is an integer number (1893558303).

Almost surely, 2^21125411540 is an apocalyptic number.

21125411540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21125411540 is an abundant number, since it is smaller than the sum of its proper divisors (24319987732).

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

21125411540 is a wasteful number, since it uses less digits than its factorization.

21125411540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25762747 (or 25762745 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 26.

Adding to 21125411540 its reverse (4511452112), we get a palindrome (25636863652).

The spelling of 21125411540 in words is "twenty-one billion, one hundred twenty-five million, four hundred eleven thousand, five hundred forty".