21545552305243 has 4 divisors (see below), whose sum is σ = 21545591721160. Its totient is φ = 21545512889328.

The previous prime is 21545552305231. The next prime is 21545552305253. The reversal of 21545552305243 is 34250325554512.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21545552305243 - 2³⁷ = 21408113351771 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21545552305193 and 21545552305202.

It is not an unprimeable number, because it can be changed into a prime (21545552305213) 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, 18876330 + ... + 19985167.

It is an arithmetic number, because the mean of its divisors is an integer number (5386397930290).

Almost surely, 2^{21545552305243} is an apocalyptic number.

21545552305243 is a deficient number, since it is larger than the sum of its proper divisors (39415917).

21545552305243 is an equidigital number, since it uses as much as digits as its factorization.

21545552305243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39415916.

The product of its (nonzero) digits is 3600000, while the sum is 46.

Adding to 21545552305243 its reverse (34250325554512), we get a palindrome (55795877859755).

The spelling of 21545552305243 in words is "twenty-one trillion, five hundred forty-five billion, five hundred fifty-two million, three hundred five thousand, two hundred forty-three".