21616969 has 4 divisors (see below), whose sum is σ = 23582160. Its totient is φ = 19651780.

The previous prime is 21616967. The next prime is 21616999. The reversal of 21616969 is 96961612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21616969 - 2¹ = 21616967 is a prime.

It is a super-2 number, since 2×21616969² = 934586697493922, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

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

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21616961) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 982579 + ... + 982600.

It is an arithmetic number, because the mean of its divisors is an integer number (5895540).

Almost surely, 2^21616969 is an apocalyptic number.

It is an amenable number.

21616969 is a deficient number, since it is larger than the sum of its proper divisors (1965191).

21616969 is a wasteful number, since it uses less digits than its factorization.

21616969 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1965190.

The product of its digits is 34992, while the sum is 40.

The square root of 21616969 is about 4649.4052307795. The cubic root of 21616969 is about 278.5682397431.

The spelling of 21616969 in words is "twenty-one million, six hundred sixteen thousand, nine hundred sixty-nine".