21787361 has 8 divisors (see below), whose sum is σ = 22238184. Its totient is φ = 21340800.

The previous prime is 21787313. The next prime is 21787373. The reversal of 21787361 is 16378712.

It can be written as a sum of positive squares in 4 ways, for example, as 118336 + 21669025 = 344^2 + 4655^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21787361 - 2²² = 17593057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21787301) 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, 10511 + ... + 12411.

It is an arithmetic number, because the mean of its divisors is an integer number (2779773).

Almost surely, 2^21787361 is an apocalyptic number.

It is an amenable number.

21787361 is a deficient number, since it is larger than the sum of its proper divisors (450823).

21787361 is a wasteful number, since it uses less digits than its factorization.

21787361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2131.

The product of its digits is 14112, while the sum is 35.

The square root of 21787361 is about 4667.6933275441. The cubic root of 21787361 is about 279.2982469448.

It can be divided in two parts, 217 and 87361, that added together give a palindrome (87578).

The spelling of 21787361 in words is "twenty-one million, seven hundred eighty-seven thousand, three hundred sixty-one".