21535003421 has 2 divisors, whose sum is σ = 21535003422. Its totient is φ = 21535003420.

The previous prime is 21535003379. The next prime is 21535003447. The reversal of 21535003421 is 12430053512.

It is a happy number.

It is an a-pointer prime, because the next prime (21535003447) can be obtained adding 21535003421 to its sum of digits (26).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17526847321 + 4008156100 = 132389^2 + 63310^2 .

It is a cyclic number.

It is not a de Polignac number, because 21535003421 - 2¹⁰ = 21535002397 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21535003471) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10767501710 + 10767501711.

It is an arithmetic number, because the mean of its divisors is an integer number (10767501711).

Almost surely, 2^21535003421 is an apocalyptic number.

It is an amenable number.

21535003421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21535003421 is an equidigital number, since it uses as much as digits as its factorization.

21535003421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3600, while the sum is 26.

Adding to 21535003421 its reverse (12430053512), we get a palindrome (33965056933).

The spelling of 21535003421 in words is "twenty-one billion, five hundred thirty-five million, three thousand, four hundred twenty-one".