20905537 has 4 divisors (see below), whose sum is σ = 21121156. Its totient is φ = 20689920.

The previous prime is 20905519. The next prime is 20905559. The reversal of 20905537 is 73550902.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16941456 + 3964081 = 4116^2 + 1991^2 .

It is a cyclic number.

It is not a de Polignac number, because 20905537 - 2²³ = 12516929 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20905499 and 20905508.

It is not an unprimeable number, because it can be changed into a prime (20905517) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107664 + ... + 107857.

It is an arithmetic number, because the mean of its divisors is an integer number (5280289).

Almost surely, 2^20905537 is an apocalyptic number.

It is an amenable number.

20905537 is a deficient number, since it is larger than the sum of its proper divisors (215619).

20905537 is an equidigital number, since it uses as much as digits as its factorization.

20905537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215618.

The product of its (nonzero) digits is 9450, while the sum is 31.

The square root of 20905537 is about 4572.2573199679. The cubic root of 20905537 is about 275.4781192170.

The spelling of 20905537 in words is "twenty million, nine hundred five thousand, five hundred thirty-seven".