20910805021 has 2 divisors, whose sum is σ = 20910805022. Its totient is φ = 20910805020.

The previous prime is 20910805009. The next prime is 20910805033. The reversal of 20910805021 is 12050801902.

It is a balanced prime because it is at equal distance from previous prime (20910805009) and next prime (20910805033).

It can be written as a sum of positive squares in only one way, i.e., 13607222500 + 7303582521 = 116650^2 + 85461^2 .

It is a cyclic number.

It is not a de Polignac number, because 20910805021 - 2¹⁹ = 20910280733 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20910805061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10455402510 + 10455402511.

It is an arithmetic number, because the mean of its divisors is an integer number (10455402511).

Almost surely, 2^20910805021 is an apocalyptic number.

It is an amenable number.

20910805021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20910805021 is an equidigital number, since it uses as much as digits as its factorization.

20910805021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 28.

The spelling of 20910805021 in words is "twenty billion, nine hundred ten million, eight hundred five thousand, twenty-one".