21590823421 has 2 divisors, whose sum is σ = 21590823422. Its totient is φ = 21590823420.

The previous prime is 21590823407. The next prime is 21590823469. The reversal of 21590823421 is 12432809512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19759924900 + 1830898521 = 140570^2 + 42789^2 .

It is a cyclic number.

It is not a de Polignac number, because 21590823421 - 2⁵ = 21590823389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21590823721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10795411710 + 10795411711.

It is an arithmetic number, because the mean of its divisors is an integer number (10795411711).

Almost surely, 2^21590823421 is an apocalyptic number.

It is an amenable number.

21590823421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21590823421 is an equidigital number, since it uses as much as digits as its factorization.

21590823421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34560, while the sum is 37.

The spelling of 21590823421 in words is "twenty-one billion, five hundred ninety million, eight hundred twenty-three thousand, four hundred twenty-one".