21180789 has 18 divisors (see below), whose sum is σ = 35590230. Its totient is φ = 12103056.

The previous prime is 21180779. The next prime is 21180799. The reversal of 21180789 is 98708112.

It is an interprime number because it is at equal distance from previous prime (21180779) and next prime (21180799).

It can be written as a sum of positive squares in only one way, i.e., 17994564 + 3186225 = 4242^2 + 1785^2 .

It is not a de Polignac number, because 21180789 - 2⁴ = 21180773 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21180739) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 23574 + ... + 24455.

It is an arithmetic number, because the mean of its divisors is an integer number (1977235).

Almost surely, 2^21180789 is an apocalyptic number.

It is an amenable number.

21180789 is a deficient number, since it is larger than the sum of its proper divisors (14409441).

21180789 is a wasteful number, since it uses less digits than its factorization.

21180789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48049 (or 48039 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 21180789 is about 4602.2591191718. The cubic root of 21180789 is about 276.6818757465.

The spelling of 21180789 in words is "twenty-one million, one hundred eighty thousand, seven hundred eighty-nine".