20921221963 has 4 divisors (see below), whose sum is σ = 21642643440. Its totient is φ = 20199800488.

The previous prime is 20921221949. The next prime is 20921221969. The reversal of 20921221963 is 36912212902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 36912212902 = 2 ⋅18456106451.

It is a cyclic number.

It is not a de Polignac number, because 20921221963 - 2⁵ = 20921221931 is a prime.

It is a super-2 number, since 2×20921221963² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20921221969) 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, 360710695 + ... + 360710752.

It is an arithmetic number, because the mean of its divisors is an integer number (5410660860).

Almost surely, 2^20921221963 is an apocalyptic number.

20921221963 is a deficient number, since it is larger than the sum of its proper divisors (721421477).

20921221963 is an equidigital number, since it uses as much as digits as its factorization.

20921221963 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 721421476.

The product of its (nonzero) digits is 23328, while the sum is 37.

The spelling of 20921221963 in words is "twenty billion, nine hundred twenty-one million, two hundred twenty-one thousand, nine hundred sixty-three".