21630813 has 8 divisors (see below), whose sum is σ = 28864800. Its totient is φ = 14408688.

The previous prime is 21630779. The next prime is 21630841. The reversal of 21630813 is 31803612.

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

It is not a de Polignac number, because 21630813 - 2¹⁰ = 21629789 is a prime.

It is a super-3 number, since 3×21630813³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21630853) by changing a digit.

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, 3018 + ... + 7236.

It is an arithmetic number, because the mean of its divisors is an integer number (3608100).

Almost surely, 2^21630813 is an apocalyptic number.

It is an amenable number.

21630813 is a deficient number, since it is larger than the sum of its proper divisors (7233987).

21630813 is a wasteful number, since it uses less digits than its factorization.

21630813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5931.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 21630813 is about 4650.8937850697. The cubic root of 21630813 is about 278.6276942044.

The spelling of 21630813 in words is "twenty-one million, six hundred thirty thousand, eight hundred thirteen".