21452139421 has 2 divisors, whose sum is σ = 21452139422. Its totient is φ = 21452139420.

The previous prime is 21452139361. The next prime is 21452139427. The reversal of 21452139421 is 12493125412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15536376025 + 5915763396 = 124645^2 + 76914^2 .

It is a cyclic number.

It is not a de Polignac number, because 21452139421 - 2¹¹ = 21452137373 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21452139427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10726069710 + 10726069711.

It is an arithmetic number, because the mean of its divisors is an integer number (10726069711).

Almost surely, 2^21452139421 is an apocalyptic number.

It is an amenable number.

21452139421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21452139421 is an equidigital number, since it uses as much as digits as its factorization.

21452139421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17280, while the sum is 34.

The spelling of 21452139421 in words is "twenty-one billion, four hundred fifty-two million, one hundred thirty-nine thousand, four hundred twenty-one".