19521288421 has 2 divisors, whose sum is σ = 19521288422. Its totient is φ = 19521288420.

The previous prime is 19521288419. The next prime is 19521288463. The reversal of 19521288421 is 12488212591.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19421488321 + 99800100 = 139361^2 + 9990^2 .

It is a cyclic number.

It is not a de Polignac number, because 19521288421 - 2¹ = 19521288419 is a prime.

Together with 19521288419, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19521238421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9760644210 + 9760644211.

It is an arithmetic number, because the mean of its divisors is an integer number (9760644211).

Almost surely, 2^19521288421 is an apocalyptic number.

It is an amenable number.

19521288421 is a deficient number, since it is larger than the sum of its proper divisors (1).

19521288421 is an equidigital number, since it uses as much as digits as its factorization.

19521288421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 92160, while the sum is 43.

The spelling of 19521288421 in words is "nineteen billion, five hundred twenty-one million, two hundred eighty-eight thousand, four hundred twenty-one".