21617946 has 24 divisors (see below), whose sum is σ = 53530464. Its totient is φ = 6176520.

The previous prime is 21617927. The next prime is 21617969. The reversal of 21617946 is 64971612.

It is a self number, because there is not a number n which added to its sum of digits gives 21617946.

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 11 ways as a sum of consecutive naturals, for example, 85660 + ... + 85911.

It is an arithmetic number, because the mean of its divisors is an integer number (2230436).

Almost surely, 2^21617946 is an apocalyptic number.

21617946 is an abundant number, since it is smaller than the sum of its proper divisors (31912518).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21617946 is a wasteful number, since it uses less digits than its factorization.

21617946 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 171586 (or 171583 counting only the distinct ones).

The product of its digits is 18144, while the sum is 36.

The square root of 21617946 is about 4649.5102967947. The cubic root of 21617946 is about 278.5724364010.

It can be divided in two parts, 216179 and 46, that added together give a square (216225 = 465²).

The spelling of 21617946 in words is "twenty-one million, six hundred seventeen thousand, nine hundred forty-six".