20421635155003 has 4 divisors (see below), whose sum is σ = 20495359469920. Its totient is φ = 20347910840088.

The previous prime is 20421635154937. The next prime is 20421635155021. The reversal of 20421635155003 is 30055153612402.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20421635155003 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20421635155093) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36862157043 + ... + 36862157596.

It is an arithmetic number, because the mean of its divisors is an integer number (5123839867480).

Almost surely, 2^{20421635155003} is an apocalyptic number.

20421635155003 is a deficient number, since it is larger than the sum of its proper divisors (73724314917).

20421635155003 is an equidigital number, since it uses as much as digits as its factorization.

20421635155003 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73724314916.

The product of its (nonzero) digits is 108000, while the sum is 37.

Adding to 20421635155003 its reverse (30055153612402), we get a palindrome (50476788767405).

The spelling of 20421635155003 in words is "twenty trillion, four hundred twenty-one billion, six hundred thirty-five million, one hundred fifty-five thousand, three".