21201431243 has 4 divisors (see below), whose sum is σ = 21207200880. Its totient is φ = 21195661608.

The previous prime is 21201431233. The next prime is 21201431249. The reversal of 21201431243 is 34213410212.

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 21201431243 - 2⁴ = 21201431227 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21201431249) 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, 2879303 + ... + 2886656.

It is an arithmetic number, because the mean of its divisors is an integer number (5301800220).

Almost surely, 2^21201431243 is an apocalyptic number.

21201431243 is a deficient number, since it is larger than the sum of its proper divisors (5769637).

21201431243 is an equidigital number, since it uses as much as digits as its factorization.

21201431243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5769636.

The product of its (nonzero) digits is 1152, while the sum is 23.

Adding to 21201431243 its reverse (34213410212), we get a palindrome (55414841455).

The spelling of 21201431243 in words is "twenty-one billion, two hundred one million, four hundred thirty-one thousand, two hundred forty-three".