20704921 has 2 divisors, whose sum is σ = 20704922. Its totient is φ = 20704920.

The previous prime is 20704913. The next prime is 20704933. The reversal of 20704921 is 12940702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20602521 + 102400 = 4539^2 + 320^2 .

It is a cyclic number.

It is not a de Polignac number, because 20704921 - 2³ = 20704913 is a prime.

It is equal to p_1312486 and since 20704921 and 1312486 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (20704951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10352460 + 10352461.

It is an arithmetic number, because the mean of its divisors is an integer number (10352461).

Almost surely, 2^20704921 is an apocalyptic number.

It is an amenable number.

20704921 is a deficient number, since it is larger than the sum of its proper divisors (1).

20704921 is an equidigital number, since it uses as much as digits as its factorization.

20704921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 20704921 is about 4550.2660361785. The cubic root of 20704921 is about 274.5940942824.

The spelling of 20704921 in words is "twenty million, seven hundred four thousand, nine hundred twenty-one".