21191001 has 8 divisors (see below), whose sum is σ = 30428160. Its totient is φ = 13040592.

The previous prime is 21190997. The next prime is 21191041. The reversal of 21191001 is 10019112.

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

It is not a de Polignac number, because 21191001 - 2² = 21190997 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21191041) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 271641 + ... + 271718.

It is an arithmetic number, because the mean of its divisors is an integer number (3803520).

Almost surely, 2^21191001 is an apocalyptic number.

It is an amenable number.

21191001 is a deficient number, since it is larger than the sum of its proper divisors (9237159).

21191001 is a wasteful number, since it uses less digits than its factorization.

21191001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 543375.

The product of its (nonzero) digits is 18, while the sum is 15.

The square root of 21191001 is about 4603.3684406095. The cubic root of 21191001 is about 276.7263346089.

The spelling of 21191001 in words is "twenty-one million, one hundred ninety-one thousand, one".