20491001 has 8 divisors (see below), whose sum is σ = 21744360. Its totient is φ = 19243008.

The previous prime is 20490997. The next prime is 20491039. The reversal of 20491001 is 10019402.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 16410601 + 4080400 = 4051^2 + 2020^2 .

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 20491001 - 2² = 20490997 is a prime.

It is a super-2 number, since 2×20491001² = 839762243964002, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is not an unprimeable number, because it can be changed into a prime (20491301) 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, 8765 + ... + 10853.

It is an arithmetic number, because the mean of its divisors is an integer number (2718045).

Almost surely, 2^20491001 is an apocalyptic number.

It is an amenable number.

20491001 is a deficient number, since it is larger than the sum of its proper divisors (1253359).

20491001 is a wasteful number, since it uses less digits than its factorization.

20491001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2683.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 20491001 is about 4526.6986866811. The cubic root of 20491001 is about 273.6451308385.

The spelling of 20491001 in words is "twenty million, four hundred ninety-one thousand, one".