21253430542541 has 4 divisors (see below), whose sum is σ = 21302742446784. Its totient is φ = 21204118638300.

The previous prime is 21253430542537. The next prime is 21253430542543. The reversal of 21253430542541 is 14524503435212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21253430542541 - 2² = 21253430542537 is a prime.

It is a super-4 number, since 4×21253430542541⁴ (a number of 54 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253430542543) 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, 24655951475 + ... + 24655952336.

It is an arithmetic number, because the mean of its divisors is an integer number (5325685611696).

Almost surely, 2^{21253430542541} is an apocalyptic number.

It is an amenable number.

21253430542541 is a deficient number, since it is larger than the sum of its proper divisors (49311904243).

21253430542541 is an equidigital number, since it uses as much as digits as its factorization.

21253430542541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49311904242.

The product of its (nonzero) digits is 576000, while the sum is 41.

Adding to 21253430542541 its reverse (14524503435212), we get a palindrome (35777933977753).

The spelling of 21253430542541 in words is "twenty-one trillion, two hundred fifty-three billion, four hundred thirty million, five hundred forty-two thousand, five hundred forty-one".