20628761 has 2 divisors, whose sum is σ = 20628762. Its totient is φ = 20628760.

The previous prime is 20628757. The next prime is 20628767. The reversal of 20628761 is 16782602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20611600 + 17161 = 4540^2 + 131^2 .

It is a cyclic number.

It is not a de Polignac number, because 20628761 - 2² = 20628757 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20628767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10314380 + 10314381.

It is an arithmetic number, because the mean of its divisors is an integer number (10314381).

Almost surely, 2^20628761 is an apocalyptic number.

It is an amenable number.

20628761 is a deficient number, since it is larger than the sum of its proper divisors (1).

20628761 is an equidigital number, since it uses as much as digits as its factorization.

20628761 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 20628761 is about 4541.8895847433. The cubic root of 20628761 is about 274.2569959883.

The spelling of 20628761 in words is "twenty million, six hundred twenty-eight thousand, seven hundred sixty-one".