20312989 has 2 divisors, whose sum is σ = 20312990.
Its totient is φ = 20312988.
The previous prime is 20312983. The next prime is 20313001. The reversal of 20312989 is 98921302.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 17935225 + 2377764 = 4235^2 + 1542^2
It is a cyclic number.
It is not a de Polignac number, because 20312989 - 27 = 20312861 is a prime.
It is a super-2 number, since 2×203129892 = 825235044228242, which contains 22 as substring.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (20312983) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10156494 + 10156495.
It is an arithmetic number, because the mean of its divisors is an integer number (10156495).
Almost surely, 220312989 is an apocalyptic number.
It is an amenable number.
20312989 is a deficient number, since it is larger than the sum of its proper divisors (1).
20312989 is an equidigital number, since it uses as much as digits as its factorization.
20312989 is an evil number, because the sum of its binary digits is even.
The product of its (nonzero) digits is 7776, while the sum is 34.
The square root of 20312989 is about 4506.9933436827.
The cubic root of 20312989 is about 272.8504102497.
The spelling of 20312989 in words is "twenty million, three hundred twelve thousand, nine hundred eighty-nine".