20621191 has 2 divisors, whose sum is σ = 20621192. Its totient is φ = 20621190.

The previous prime is 20621189. The next prime is 20621239. The reversal of 20621191 is 19112602.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20621191 - 2¹ = 20621189 is a prime.

Together with 20621189, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20621131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10310595 + 10310596.

It is an arithmetic number, because the mean of its divisors is an integer number (10310596).

Almost surely, 2^20621191 is an apocalyptic number.

20621191 is a deficient number, since it is larger than the sum of its proper divisors (1).

20621191 is an equidigital number, since it uses as much as digits as its factorization.

20621191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 22.

The square root of 20621191 is about 4541.0561546847. The cubic root of 20621191 is about 274.2234444585.

Adding to 20621191 its reverse (19112602), we get a palindrome (39733793).

The spelling of 20621191 in words is "twenty million, six hundred twenty-one thousand, one hundred ninety-one".