21630819 has 8 divisors (see below), whose sum is σ = 32961280. Its totient is φ = 12360456.

The previous prime is 21630779. The next prime is 21630841. The reversal of 21630819 is 91803612.

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

It is not a de Polignac number, because 21630819 - 2⁸ = 21630563 is a prime.

It is a super-2 number, since 2×21630819² = 935784661221522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21630899) 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, 514999 + ... + 515040.

It is an arithmetic number, because the mean of its divisors is an integer number (4120160).

Almost surely, 2^21630819 is an apocalyptic number.

21630819 is a deficient number, since it is larger than the sum of its proper divisors (11330461).

21630819 is a wasteful number, since it uses less digits than its factorization.

21630819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1030049.

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 21630819 is about 4650.8944301070. The cubic root of 21630819 is about 278.6277199665.

The spelling of 21630819 in words is "twenty-one million, six hundred thirty thousand, eight hundred nineteen".