21010221109 has 4 divisors (see below), whose sum is σ = 22116022240. Its totient is φ = 19904419980.

The previous prime is 21010221073. The next prime is 21010221121. The reversal of 21010221109 is 90112201012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21010221109 - 2⁹ = 21010220597 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19), and also a Moran number because the ratio is a prime number: 1105801111 = 21010221109 / (2 + 1 + 0 + 1 + 0 + 2 + 2 + 1 + 1 + 0 + 9).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21010221209) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 552900537 + ... + 552900574.

It is an arithmetic number, because the mean of its divisors is an integer number (5529005560).

Almost surely, 2^21010221109 is an apocalyptic number.

It is an amenable number.

21010221109 is a deficient number, since it is larger than the sum of its proper divisors (1105801131).

21010221109 is a wasteful number, since it uses less digits than its factorization.

21010221109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1105801130.

The product of its (nonzero) digits is 72, while the sum is 19.

The spelling of 21010221109 in words is "twenty-one billion, ten million, two hundred twenty-one thousand, one hundred nine".