21535503421 has 16 divisors (see below), whose sum is σ = 22683322368. Its totient is φ = 20418652800.

The previous prime is 21535503419. The next prime is 21535503487. The reversal of 21535503421 is 12430553512.

It is a cyclic number.

It is not a de Polignac number, because 21535503421 - 2¹ = 21535503419 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21535003421) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1374196 + ... + 1389778.

It is an arithmetic number, because the mean of its divisors is an integer number (1417707648).

Almost surely, 2^21535503421 is an apocalyptic number.

It is an amenable number.

21535503421 is a deficient number, since it is larger than the sum of its proper divisors (1147818947).

21535503421 is a wasteful number, since it uses less digits than its factorization.

21535503421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16572.

The product of its (nonzero) digits is 18000, while the sum is 31.

The spelling of 21535503421 in words is "twenty-one billion, five hundred thirty-five million, five hundred three thousand, four hundred twenty-one".