20891070 has 72 divisors (see below), whose sum is σ = 57415176. Its totient is φ = 5269536.

The previous prime is 20891047. The next prime is 20891071. The reversal of 20891070 is 7019802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20891071) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 32169 + ... + 32811.

It is an arithmetic number, because the mean of its divisors is an integer number (797433).

Almost surely, 2^20891070 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20891070, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28707588).

20891070 is an abundant number, since it is smaller than the sum of its proper divisors (36524106).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20891070 is a wasteful number, since it uses less digits than its factorization.

20891070 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 694 (or 672 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 27.

The square root of 20891070 is about 4570.6750048543. The cubic root of 20891070 is about 275.4145593156.

The spelling of 20891070 in words is "twenty million, eight hundred ninety-one thousand, seventy".