21091546 has 16 divisors (see below), whose sum is σ = 36403200. Its totient is φ = 8977680.

The previous prime is 21091523. The next prime is 21091547. The reversal of 21091546 is 64519012.

It is not an unprimeable number, because it can be changed into a prime (21091547) 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, 2970 + ... + 7141.

It is an arithmetic number, because the mean of its divisors is an integer number (2275200).

Almost surely, 2^21091546 is an apocalyptic number.

21091546 is a deficient number, since it is larger than the sum of its proper divisors (15311654).

21091546 is a wasteful number, since it uses less digits than its factorization.

21091546 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10269.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 21091546 is about 4592.5533203219. The cubic root of 21091546 is about 276.2927388268.

It can be divided in two parts, 2109 and 1546, that added together give a triangular number (3655 = T₈₅).

The spelling of 21091546 in words is "twenty-one million, ninety-one thousand, five hundred forty-six".