20660621 has 2 divisors, whose sum is σ = 20660622. Its totient is φ = 20660620.

The previous prime is 20660617. The next prime is 20660659. The reversal of 20660621 is 12606602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19483396 + 1177225 = 4414^2 + 1085^2 .

It is a cyclic number.

It is not a de Polignac number, because 20660621 - 2² = 20660617 is a prime.

It is a super-2 number, since 2×20660621² = 853722520211282, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20660611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10330310 + 10330311.

It is an arithmetic number, because the mean of its divisors is an integer number (10330311).

Almost surely, 2^20660621 is an apocalyptic number.

It is an amenable number.

20660621 is a deficient number, since it is larger than the sum of its proper divisors (1).

20660621 is an equidigital number, since it uses as much as digits as its factorization.

20660621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 20660621 is about 4545.3955823448. The cubic root of 20660621 is about 274.3981150369.

The spelling of 20660621 in words is "twenty million, six hundred sixty thousand, six hundred twenty-one".