21764045 has 8 divisors (see below), whose sum is σ = 26220024. Its totient is φ = 17342464.

The previous prime is 21764027. The next prime is 21764051. The reversal of 21764045 is 54046712.

It can be written as a sum of positive squares in 4 ways, for example, as 6421156 + 15342889 = 2534^2 + 3917^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21764045 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21763999 and 21764017.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7184 + ... + 9753.

It is an arithmetic number, because the mean of its divisors is an integer number (3277503).

Almost surely, 2^21764045 is an apocalyptic number.

It is an amenable number.

21764045 is a deficient number, since it is larger than the sum of its proper divisors (4455979).

21764045 is a wasteful number, since it uses less digits than its factorization.

21764045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17199.

The product of its (nonzero) digits is 6720, while the sum is 29.

The square root of 21764045 is about 4665.1950655894. The cubic root of 21764045 is about 279.1985799511.

The spelling of 21764045 in words is "twenty-one million, seven hundred sixty-four thousand, forty-five".