21641630 has 16 divisors (see below), whose sum is σ = 39042000. Its totient is φ = 8637312.

The previous prime is 21641611. The next prime is 21641671. The reversal of 21641630 is 3614612.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21641596 and 21641605.

It is a congruent number.

It is an unprimeable number.

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, 2822 + ... + 7158.

It is an arithmetic number, because the mean of its divisors is an integer number (2440125).

Almost surely, 2^21641630 is an apocalyptic number.

21641630 is a deficient number, since it is larger than the sum of its proper divisors (17400370).

21641630 is a wasteful number, since it uses less digits than its factorization.

21641630 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4843.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21641630 is about 4652.0565344802. The cubic root of 21641630 is about 278.6741312556.

The spelling of 21641630 in words is "twenty-one million, six hundred forty-one thousand, six hundred thirty".