20423989 has 2 divisors, whose sum is σ = 20423990. Its totient is φ = 20423988.

The previous prime is 20423969. The next prime is 20424043. The reversal of 20423989 is 98932402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13359025 + 7064964 = 3655^2 + 2658^2 .

It is a cyclic number.

It is not a de Polignac number, because 20423989 - 2¹⁵ = 20391221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20423929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10211994 + 10211995.

It is an arithmetic number, because the mean of its divisors is an integer number (10211995).

Almost surely, 2^20423989 is an apocalyptic number.

It is an amenable number.

20423989 is a deficient number, since it is larger than the sum of its proper divisors (1).

20423989 is an equidigital number, since it uses as much as digits as its factorization.

20423989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 31104, while the sum is 37.

The square root of 20423989 is about 4519.2907629406. The cubic root of 20423989 is about 273.3465032652.

It can be divided in two parts, 20423 and 989, that added together give a palindrome (21412).

The spelling of 20423989 in words is "twenty million, four hundred twenty-three thousand, nine hundred eighty-nine".