21045771 has 16 divisors (see below), whose sum is σ = 31292800. Its totient is φ = 13979304.

The previous prime is 21045769. The next prime is 21045781. The reversal of 21045771 is 17754012.

It is not a de Polignac number, because 21045771 - 2¹ = 21045769 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21045701) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7020 + ... + 9558.

It is an arithmetic number, because the mean of its divisors is an integer number (1955800).

Almost surely, 2^21045771 is an apocalyptic number.

21045771 is a deficient number, since it is larger than the sum of its proper divisors (10247029).

21045771 is a wasteful number, since it uses less digits than its factorization.

21045771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2855 (or 2849 counting only the distinct ones).

The product of its (nonzero) digits is 1960, while the sum is 27.

The square root of 21045771 is about 4587.5670022355. The cubic root of 21045771 is about 276.0927145983.

Adding to 21045771 its reverse (17754012), we get a palindrome (38799783).

It can be divided in two parts, 2104 and 5771, that added together give a triangular number (7875 = T₁₂₅).

The spelling of 21045771 in words is "twenty-one million, forty-five thousand, seven hundred seventy-one".