20417891 has 4 divisors (see below), whose sum is σ = 21988512. Its totient is φ = 18847272.

The previous prime is 20417863. The next prime is 20417897. The reversal of 20417891 is 19871402.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20417891 - 2¹⁸ = 20155747 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20417897) 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, 785291 + ... + 785316.

It is an arithmetic number, because the mean of its divisors is an integer number (5497128).

Almost surely, 2^20417891 is an apocalyptic number.

20417891 is a deficient number, since it is larger than the sum of its proper divisors (1570621).

20417891 is a wasteful number, since it uses less digits than its factorization.

20417891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1570620.

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 20417891 is about 4518.6160491903. The cubic root of 20417891 is about 273.3192961593.

The spelling of 20417891 in words is "twenty million, four hundred seventeen thousand, eight hundred ninety-one".