20505407 has 16 divisors (see below), whose sum is σ = 23100000. Its totient is φ = 18071424.

The previous prime is 20505379. The next prime is 20505409. The reversal of 20505407 is 70450502.

It is a cyclic number.

It is not a de Polignac number, because 20505407 - 2⁸ = 20505151 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20505409) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 40844 + ... + 41342.

It is an arithmetic number, because the mean of its divisors is an integer number (1443750).

Almost surely, 2^20505407 is an apocalyptic number.

20505407 is a deficient number, since it is larger than the sum of its proper divisors (2594593).

20505407 is a wasteful number, since it uses less digits than its factorization.

20505407 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 650.

The product of its (nonzero) digits is 1400, while the sum is 23.

The square root of 20505407 is about 4528.2896329630. The cubic root of 20505407 is about 273.7092436701.

Adding to 20505407 its reverse (70450502), we get a palindrome (90955909).

The spelling of 20505407 in words is "twenty million, five hundred five thousand, four hundred seven".