20621533 has 2 divisors, whose sum is σ = 20621534. Its totient is φ = 20621532.

The previous prime is 20621519. The next prime is 20621537. The reversal of 20621533 is 33512602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17530969 + 3090564 = 4187^2 + 1758^2 .

It is a cyclic number.

It is not a de Polignac number, because 20621533 - 2¹⁷ = 20490461 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20621537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10310766 + 10310767.

It is an arithmetic number, because the mean of its divisors is an integer number (10310767).

Almost surely, 2^20621533 is an apocalyptic number.

It is an amenable number.

20621533 is a deficient number, since it is larger than the sum of its proper divisors (1).

20621533 is an equidigital number, since it uses as much as digits as its factorization.

20621533 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1080, while the sum is 22.

The square root of 20621533 is about 4541.0938109667. The cubic root of 20621533 is about 274.2249604379.

The spelling of 20621533 in words is "twenty million, six hundred twenty-one thousand, five hundred thirty-three".