21634918 has 12 divisors (see below), whose sum is σ = 33084828. Its totient is φ = 10610600.

The previous prime is 21634913. The next prime is 21634919. The reversal of 21634918 is 81943612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21634913) 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 5 ways as a sum of consecutive naturals, for example, 3693 + ... + 7543.

It is an arithmetic number, because the mean of its divisors is an integer number (2757069).

Almost surely, 2^21634918 is an apocalyptic number.

21634918 is a deficient number, since it is larger than the sum of its proper divisors (11449910).

21634918 is an equidigital number, since it uses as much as digits as its factorization.

21634918 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3959 (or 3906 counting only the distinct ones).

The product of its digits is 10368, while the sum is 34.

The square root of 21634918 is about 4651.3350771580. The cubic root of 21634918 is about 278.6453186666.

The spelling of 21634918 in words is "twenty-one million, six hundred thirty-four thousand, nine hundred eighteen".