21010221091 has 16 divisors (see below), whose sum is σ = 21364469568. Its totient is φ = 20659392000.

The previous prime is 21010221073. The next prime is 21010221121. The reversal of 21010221091 is 19012201012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21010221091 - 2⁷ = 21010220963 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21010221391) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9830575 + ... + 9832711.

It is an arithmetic number, because the mean of its divisors is an integer number (1335279348).

Almost surely, 2^21010221091 is an apocalyptic number.

21010221091 is a deficient number, since it is larger than the sum of its proper divisors (354248477).

21010221091 is a wasteful number, since it uses less digits than its factorization.

21010221091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2862.

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

The spelling of 21010221091 in words is "twenty-one billion, ten million, two hundred twenty-one thousand, ninety-one".