20620405 has 16 divisors (see below), whose sum is σ = 28216944. Its totient is φ = 14330880.

The previous prime is 20620399. The next prime is 20620423. The reversal of 20620405 is 50402602.

It can be written as a sum of positive squares in 8 ways, for example, as 2566404 + 18054001 = 1602^2 + 4249^2 .

It is not a de Polignac number, because 20620405 - 2⁵ = 20620373 is a prime.

It is a super-2 number, since 2×20620405² = 850402204728050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8226 + ... + 10435.

It is an arithmetic number, because the mean of its divisors is an integer number (1763559).

Almost surely, 2^20620405 is an apocalyptic number.

It is an amenable number.

20620405 is a deficient number, since it is larger than the sum of its proper divisors (7596539).

20620405 is a wasteful number, since it uses less digits than its factorization.

20620405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18696.

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 20620405 is about 4540.9696101163. The cubic root of 20620405 is about 274.2199603021.

It can be divided in two parts, 20620 and 405, that added together give a square (21025 = 145²).

The spelling of 20620405 in words is "twenty million, six hundred twenty thousand, four hundred five".