21100789 has 2 divisors, whose sum is σ = 21100790. Its totient is φ = 21100788.

The previous prime is 21100787. The next prime is 21100813. The reversal of 21100789 is 98700112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11675889 + 9424900 = 3417^2 + 3070^2 .

It is a cyclic number.

It is not a de Polignac number, because 21100789 - 2¹ = 21100787 is a prime.

Together with 21100787, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21100787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550394 + 10550395.

It is an arithmetic number, because the mean of its divisors is an integer number (10550395).

Almost surely, 2^21100789 is an apocalyptic number.

It is an amenable number.

21100789 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100789 is an equidigital number, since it uses as much as digits as its factorization.

21100789 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 21100789 is about 4593.5595130574. The cubic root of 21100789 is about 276.3330930810. Note that the first 3 decimals are identical.

The spelling of 21100789 in words is "twenty-one million, one hundred thousand, seven hundred eighty-nine".