20652721 has 2 divisors, whose sum is σ = 20652722. Its totient is φ = 20652720.

The previous prime is 20652719. The next prime is 20652743. The reversal of 20652721 is 12725602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18792225 + 1860496 = 4335^2 + 1364^2 .

It is a cyclic number.

It is not a de Polignac number, because 20652721 - 2¹ = 20652719 is a prime.

Together with 20652719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20652701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10326360 + 10326361.

It is an arithmetic number, because the mean of its divisors is an integer number (10326361).

Almost surely, 2^20652721 is an apocalyptic number.

It is an amenable number.

20652721 is a deficient number, since it is larger than the sum of its proper divisors (1).

20652721 is an equidigital number, since it uses as much as digits as its factorization.

20652721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 20652721 is about 4544.5264879853. The cubic root of 20652721 is about 274.3631367165.

The spelling of 20652721 in words is "twenty million, six hundred fifty-two thousand, seven hundred twenty-one".