20905761 has 4 divisors (see below), whose sum is σ = 27874352. Its totient is φ = 13937172.

The previous prime is 20905751. The next prime is 20905771. The reversal of 20905761 is 16750902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (20905751) and next prime (20905771).

It is a de Polignac number, because none of the positive numbers 2^k-20905761 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20905711) 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, 3484291 + ... + 3484296.

It is an arithmetic number, because the mean of its divisors is an integer number (6968588).

Almost surely, 2^20905761 is an apocalyptic number.

It is an amenable number.

20905761 is a deficient number, since it is larger than the sum of its proper divisors (6968591).

20905761 is an equidigital number, since it uses as much as digits as its factorization.

20905761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6968590.

The product of its (nonzero) digits is 3780, while the sum is 30.

The square root of 20905761 is about 4572.2818154615. The cubic root of 20905761 is about 275.4791031171.

The spelling of 20905761 in words is "twenty million, nine hundred five thousand, seven hundred sixty-one".