20907421 has 2 divisors, whose sum is σ = 20907422. Its totient is φ = 20907420.

The previous prime is 20907409. The next prime is 20907449. The reversal of 20907421 is 12470902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20124196 + 783225 = 4486^2 + 885^2 .

It is a cyclic number.

It is not a de Polignac number, because 20907421 - 2⁵ = 20907389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20907221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10453710 + 10453711.

It is an arithmetic number, because the mean of its divisors is an integer number (10453711).

Almost surely, 2^20907421 is an apocalyptic number.

It is an amenable number.

20907421 is a deficient number, since it is larger than the sum of its proper divisors (1).

20907421 is an equidigital number, since it uses as much as digits as its factorization.

20907421 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 20907421 is about 4572.4633404763. The cubic root of 20907421 is about 275.4863943004.

The spelling of 20907421 in words is "twenty million, nine hundred seven thousand, four hundred twenty-one".