21020020001989 has 2 divisors, whose sum is σ = 21020020001990. Its totient is φ = 21020020001988.

The previous prime is 21020020001977. The next prime is 21020020002019. The reversal of 21020020001989 is 98910002002012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18345519549889 + 2674500452100 = 4283167^2 + 1635390^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020020001989 - 2³⁵ = 20985660263621 is a prime.

It is a super-2 number, since 2×21020020001989² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21020020001689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510010000994 + 10510010000995.

It is an arithmetic number, because the mean of its divisors is an integer number (10510010000995).

Almost surely, 2^{21020020001989} is an apocalyptic number.

It is an amenable number.

21020020001989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020020001989 is an equidigital number, since it uses as much as digits as its factorization.

21020020001989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 34.

The spelling of 21020020001989 in words is "twenty-one trillion, twenty billion, twenty million, one thousand, nine hundred eighty-nine".