21242785421 has 32 divisors (see below), whose sum is σ = 26451629568. Its totient is φ = 16760355840.

The previous prime is 21242785411. The next prime is 21242785423. The reversal of 21242785421 is 12458724212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21242785421 - 2¹⁰ = 21242784397 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 (21242785423) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2711516 + ... + 2719338.

It is an arithmetic number, because the mean of its divisors is an integer number (826613424).

Almost surely, 2^21242785421 is an apocalyptic number.

It is an amenable number.

21242785421 is a deficient number, since it is larger than the sum of its proper divisors (5208844147).

21242785421 is a wasteful number, since it uses less digits than its factorization.

21242785421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8981.

The product of its digits is 71680, while the sum is 38.

The spelling of 21242785421 in words is "twenty-one billion, two hundred forty-two million, seven hundred eighty-five thousand, four hundred twenty-one".