20921221403 has 4 divisors (see below), whose sum is σ = 20924095800. Its totient is φ = 20918347008.

The previous prime is 20921221397. The next prime is 20921221459. The reversal of 20921221403 is 30412212902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 30412212902 = 2 ⋅15206106451.

It is a cyclic number.

It is not a de Polignac number, because 20921221403 - 2¹⁰ = 20921220379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20921221463) 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, 1426253 + ... + 1440846.

It is an arithmetic number, because the mean of its divisors is an integer number (5231023950).

Almost surely, 2^20921221403 is an apocalyptic number.

20921221403 is a deficient number, since it is larger than the sum of its proper divisors (2874397).

20921221403 is an equidigital number, since it uses as much as digits as its factorization.

20921221403 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2874396.

The product of its (nonzero) digits is 1728, while the sum is 26.

The spelling of 20921221403 in words is "twenty billion, nine hundred twenty-one million, two hundred twenty-one thousand, four hundred three".