20501989 has 2 divisors, whose sum is σ = 20501990. Its totient is φ = 20501988.

The previous prime is 20501981. The next prime is 20502019. The reversal of 20501989 is 98910502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11168964 + 9333025 = 3342^2 + 3055^2 .

It is a cyclic number.

It is not a de Polignac number, because 20501989 - 2³ = 20501981 is a prime.

It is a super-2 number, since 2×20501989² = 840663105912242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20501981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10250994 + 10250995.

It is an arithmetic number, because the mean of its divisors is an integer number (10250995).

Almost surely, 2^20501989 is an apocalyptic number.

It is an amenable number.

20501989 is a deficient number, since it is larger than the sum of its proper divisors (1).

20501989 is an equidigital number, since it uses as much as digits as its factorization.

20501989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6480, while the sum is 34.

The square root of 20501989 is about 4527.9122120465. The cubic root of 20501989 is about 273.6940348330.

The spelling of 20501989 in words is "twenty million, five hundred one thousand, nine hundred eighty-nine".