21816077 has 4 divisors (see below), whose sum is σ = 21850140. Its totient is φ = 21782016.

The previous prime is 21816031. The next prime is 21816079. The reversal of 21816077 is 77061812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4268356 + 17547721 = 2066^2 + 4189^2 .

It is a cyclic number.

It is not a de Polignac number, because 21816077 - 2¹⁴ = 21799693 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21816079) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16052 + ... + 17357.

It is an arithmetic number, because the mean of its divisors is an integer number (5462535).

Almost surely, 2^21816077 is an apocalyptic number.

It is an amenable number.

21816077 is a deficient number, since it is larger than the sum of its proper divisors (34063).

21816077 is an equidigital number, since it uses as much as digits as its factorization.

21816077 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34062.

The product of its (nonzero) digits is 4704, while the sum is 32.

The square root of 21816077 is about 4670.7683522093. The cubic root of 21816077 is about 279.4208992080.

Adding to 21816077 its reverse (77061812), we get a palindrome (98877889).

The spelling of 21816077 in words is "twenty-one million, eight hundred sixteen thousand, seventy-seven".