20907409 has 2 divisors, whose sum is σ = 20907410. Its totient is φ = 20907408.

The previous prime is 20907389. The next prime is 20907421. The reversal of 20907409 is 90470902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20903184 + 4225 = 4572^2 + 65^2 .

It is a cyclic number.

It is not a de Polignac number, because 20907409 - 2⁵ = 20907377 is a prime.

It is not a weakly prime, because it can be changed into another prime (20907449) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10453704 + 10453705.

It is an arithmetic number, because the mean of its divisors is an integer number (10453705).

Almost surely, 2^20907409 is an apocalyptic number.

It is an amenable number.

20907409 is a deficient number, since it is larger than the sum of its proper divisors (1).

20907409 is an equidigital number, since it uses as much as digits as its factorization.

20907409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4536, while the sum is 31.

The square root of 20907409 is about 4572.4620282732. The cubic root of 20907409 is about 275.4863415945.

It can be divided in two parts, 20907 and 409, that added together give a square (21316 = 146²).

The spelling of 20907409 in words is "twenty million, nine hundred seven thousand, four hundred nine".