20625491 has 2 divisors, whose sum is σ = 20625492. Its totient is φ = 20625490.

The previous prime is 20625439. The next prime is 20625499. The reversal of 20625491 is 19452602.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20625491 - 2¹⁰ = 20624467 is a prime.

It is not a weakly prime, because it can be changed into another prime (20625499) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10312745 + 10312746.

It is an arithmetic number, because the mean of its divisors is an integer number (10312746).

Almost surely, 2^20625491 is an apocalyptic number.

20625491 is a deficient number, since it is larger than the sum of its proper divisors (1).

20625491 is an equidigital number, since it uses as much as digits as its factorization.

20625491 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 20625491 is about 4541.5295881454. The cubic root of 20625491 is about 274.2425037983.

Subtracting from 20625491 its reverse (19452602), we obtain a square (1172889 = 1083²).

The spelling of 20625491 in words is "twenty million, six hundred twenty-five thousand, four hundred ninety-one".