21630377 has 4 divisors (see below), whose sum is σ = 21642180. Its totient is φ = 21618576.

The previous prime is 21630359. The next prime is 21630383. The reversal of 21630377 is 77303612.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 2085136 + 19545241 = 1444^2 + 4421^2 .

It is a cyclic number.

It is not a de Polignac number, because 21630377 - 2¹² = 21626281 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21630337) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2498 + ... + 7035.

It is an arithmetic number, because the mean of its divisors is an integer number (5410545).

Almost surely, 2^21630377 is an apocalyptic number.

It is an amenable number.

21630377 is a deficient number, since it is larger than the sum of its proper divisors (11803).

21630377 is an equidigital number, since it uses as much as digits as its factorization.

21630377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11802.

The product of its (nonzero) digits is 5292, while the sum is 29.

The square root of 21630377 is about 4650.8469121226. The cubic root of 21630377 is about 278.6258221451.

Adding to 21630377 its reverse (77303612), we get a palindrome (98933989).

The spelling of 21630377 in words is "twenty-one million, six hundred thirty thousand, three hundred seventy-seven".