21001090521 has 8 divisors (see below), whose sum is σ = 28338821280. Its totient is φ = 13832043392.

The previous prime is 21001090499. The next prime is 21001090541. The reversal of 21001090521 is 12509010012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21001090521 - 2¹¹ = 21001088473 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21001090541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 42170616 + ... + 42171113.

It is an arithmetic number, because the mean of its divisors is an integer number (3542352660).

Almost surely, 2^21001090521 is an apocalyptic number.

It is an amenable number.

21001090521 is a deficient number, since it is larger than the sum of its proper divisors (7337730759).

21001090521 is an equidigital number, since it uses as much as digits as its factorization.

21001090521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84341815.

The product of its (nonzero) digits is 180, while the sum is 21.

The spelling of 21001090521 in words is "twenty-one billion, one million, ninety thousand, five hundred twenty-one".