20905749 has 16 divisors (see below), whose sum is σ = 31971840. Its totient is φ = 13487040.

The previous prime is 20905747. The next prime is 20905751. The reversal of 20905749 is 94750902.

It is an interprime number because it is at equal distance from previous prime (20905747) and next prime (20905751).

It is not a de Polignac number, because 20905749 - 2¹ = 20905747 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20905747) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11652 + ... + 13325.

It is an arithmetic number, because the mean of its divisors is an integer number (1998240).

Almost surely, 2^20905749 is an apocalyptic number.

It is an amenable number.

20905749 is a deficient number, since it is larger than the sum of its proper divisors (11066091).

20905749 is a wasteful number, since it uses less digits than its factorization.

20905749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25017 (or 25011 counting only the distinct ones).

The product of its (nonzero) digits is 22680, while the sum is 36.

The square root of 20905749 is about 4572.2805032063. The cubic root of 20905749 is about 275.4790504084.

The spelling of 20905749 in words is "twenty million, nine hundred five thousand, seven hundred forty-nine".