21234043357 has 2 divisors, whose sum is σ = 21234043358. Its totient is φ = 21234043356.

The previous prime is 21234043283. The next prime is 21234043367. The reversal of 21234043357 is 75334043212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21201107236 + 32936121 = 145606^2 + 5739^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21234043357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21234043367) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10617021678 + 10617021679.

It is an arithmetic number, because the mean of its divisors is an integer number (10617021679).

Almost surely, 2^21234043357 is an apocalyptic number.

It is an amenable number.

21234043357 is a deficient number, since it is larger than the sum of its proper divisors (1).

21234043357 is an equidigital number, since it uses as much as digits as its factorization.

21234043357 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 60480, while the sum is 34.

Adding to 21234043357 its reverse (75334043212), we get a palindrome (96568086569).

The spelling of 21234043357 in words is "twenty-one billion, two hundred thirty-four million, forty-three thousand, three hundred fifty-seven".