21191630 has 16 divisors (see below), whose sum is σ = 38381904. Its totient is φ = 8424000.

The previous prime is 21191623. The next prime is 21191633. The reversal of 21191630 is 3619112.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21191596 and 21191605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21191633) 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, 4871 + ... + 8130.

It is an arithmetic number, because the mean of its divisors is an integer number (2398869).

Almost surely, 2^21191630 is an apocalyptic number.

21191630 is a deficient number, since it is larger than the sum of its proper divisors (17190274).

21191630 is a wasteful number, since it uses less digits than its factorization.

21191630 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13171.

The product of its (nonzero) digits is 324, while the sum is 23.

The square root of 21191630 is about 4603.4367596395. The cubic root of 21191630 is about 276.7290725501.

The spelling of 21191630 in words is "twenty-one million, one hundred ninety-one thousand, six hundred thirty".