21616947 has 24 divisors (see below), whose sum is σ = 34582080. Its totient is φ = 12901680.

The previous prime is 21616939. The next prime is 21616949. The reversal of 21616947 is 74961612.

It is not a de Polignac number, because 21616947 - 2³ = 21616939 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (21616949) 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 23 ways as a sum of consecutive naturals, for example, 5004 + ... + 8262.

It is an arithmetic number, because the mean of its divisors is an integer number (1440920).

Almost surely, 2^21616947 is an apocalyptic number.

21616947 is a deficient number, since it is larger than the sum of its proper divisors (12965133).

21616947 is a wasteful number, since it uses less digits than its factorization.

21616947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3343 (or 3340 counting only the distinct ones).

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

The square root of 21616947 is about 4649.4028648849. The cubic root of 21616947 is about 278.5681452417.

The spelling of 21616947 in words is "twenty-one million, six hundred sixteen thousand, nine hundred forty-seven".