21987141131533 has 4 divisors (see below), whose sum is σ = 22581388189180. Its totient is φ = 21392894073888.

The previous prime is 21987141131507. The next prime is 21987141131587. The reversal of 21987141131533 is 33513114178912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16916546898729 + 5070594232804 = 4112973^2 + 2251798^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21987141131533 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 (21987141231533) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 297123528768 + ... + 297123528841.

It is an arithmetic number, because the mean of its divisors is an integer number (5645347047295).

Almost surely, 2^{21987141131533} is an apocalyptic number.

It is an amenable number.

21987141131533 is a deficient number, since it is larger than the sum of its proper divisors (594247057647).

21987141131533 is an equidigital number, since it uses as much as digits as its factorization.

21987141131533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 594247057646.

The product of its digits is 544320, while the sum is 49.

The spelling of 21987141131533 in words is "twenty-one trillion, nine hundred eighty-seven billion, one hundred forty-one million, one hundred thirty-one thousand, five hundred thirty-three".