20421506421 has 24 divisors (see below), whose sum is σ = 29996853120. Its totient is φ = 13385047200.

The previous prime is 20421506407. The next prime is 20421506423. The reversal of 20421506421 is 12460512402.

20421506421 is a `hidden beast` number, since 2 + 0 + 4 + 2 + 15 + 0 + 642 + 1 = 666.

It is not a de Polignac number, because 20421506421 - 2²⁹ = 19884635509 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20421506423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 184891 + ... + 273911.

It is an arithmetic number, because the mean of its divisors is an integer number (1249868880).

Almost surely, 2^20421506421 is an apocalyptic number.

It is an amenable number.

20421506421 is a deficient number, since it is larger than the sum of its proper divisors (9575346699).

20421506421 is a wasteful number, since it uses less digits than its factorization.

20421506421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89457 (or 89454 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The spelling of 20421506421 in words is "twenty billion, four hundred twenty-one million, five hundred six thousand, four hundred twenty-one".