20901891 has 8 divisors (see below), whose sum is σ = 29508624. Its totient is φ = 13114880.

The previous prime is 20901889. The next prime is 20901901. The reversal of 20901891 is 19810902.

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 20901891 - 2¹ = 20901889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20901821) 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, 204870 + ... + 204971.

It is an arithmetic number, because the mean of its divisors is an integer number (3688578).

Almost surely, 2^20901891 is an apocalyptic number.

20901891 is a deficient number, since it is larger than the sum of its proper divisors (8606733).

20901891 is a wasteful number, since it uses less digits than its factorization.

20901891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 409861.

The product of its (nonzero) digits is 1296, while the sum is 30.

The square root of 20901891 is about 4571.8585936138. The cubic root of 20901891 is about 275.4621034980.

The spelling of 20901891 in words is "twenty million, nine hundred one thousand, eight hundred ninety-one".