20423551 has 2 divisors, whose sum is σ = 20423552. Its totient is φ = 20423550.

The previous prime is 20423539. The next prime is 20423567. The reversal of 20423551 is 15532402.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20423551 - 2¹¹ = 20421503 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20423591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10211775 + 10211776.

It is an arithmetic number, because the mean of its divisors is an integer number (10211776).

Almost surely, 2^20423551 is an apocalyptic number.

20423551 is a deficient number, since it is larger than the sum of its proper divisors (1).

20423551 is an equidigital number, since it uses as much as digits as its factorization.

20423551 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1200, while the sum is 22.

The square root of 20423551 is about 4519.2423037496. The cubic root of 20423551 is about 273.3445492456.

Adding to 20423551 its reverse (15532402), we get a palindrome (35955953).

The spelling of 20423551 in words is "twenty million, four hundred twenty-three thousand, five hundred fifty-one".