21012011989 has 2 divisors, whose sum is σ = 21012011990. Its totient is φ = 21012011988.

The previous prime is 21012011983. The next prime is 21012012067. The reversal of 21012011989 is 98911021012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13074092964 + 7937919025 = 114342^2 + 89095^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012011989 - 2³ = 21012011981 is a prime.

It is a super-2 number, since 2×21012011989² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21012011981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506005994 + 10506005995.

It is an arithmetic number, because the mean of its divisors is an integer number (10506005995).

Almost surely, 2^21012011989 is an apocalyptic number.

It is an amenable number.

21012011989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012011989 is an equidigital number, since it uses as much as digits as its factorization.

21012011989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 34.

The spelling of 21012011989 in words is "twenty-one billion, twelve million, eleven thousand, nine hundred eighty-nine".