21630578 has 8 divisors (see below), whose sum is σ = 33564780. Its totient is φ = 10442320.

The previous prime is 21630563. The next prime is 21630593. The reversal of 21630578 is 87503612.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21630563) and next prime (21630593).

It can be written as a sum of positive squares in 2 ways, for example, as 18983449 + 2647129 = 4357^2 + 1627^2 .

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

It is a super-2 number, since 2×21630578² = 935763809228168, which contains 22 as substring.

It is an unprimeable number.

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, 186413 + ... + 186528.

Almost surely, 2^21630578 is an apocalyptic number.

21630578 is a deficient number, since it is larger than the sum of its proper divisors (11934202).

21630578 is a wasteful number, since it uses less digits than its factorization.

21630578 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 372972.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 21630578 is about 4650.8685210399. The cubic root of 21630578 is about 278.6266851848.

The spelling of 21630578 in words is "twenty-one million, six hundred thirty thousand, five hundred seventy-eight".