21616861 has 8 divisors (see below), whose sum is σ = 25557120. Its totient is φ = 17889648.

The previous prime is 21616853. The next prime is 21616883. The reversal of 21616861 is 16861612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21616861 - 2³ = 21616853 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21616801) 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, 53041 + ... + 53446.

It is an arithmetic number, because the mean of its divisors is an integer number (3194640).

Almost surely, 2^21616861 is an apocalyptic number.

It is an amenable number.

21616861 is a deficient number, since it is larger than the sum of its proper divisors (3940259).

21616861 is a wasteful number, since it uses less digits than its factorization.

21616861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106523.

The product of its digits is 3456, while the sum is 31.

The square root of 21616861 is about 4649.3936163762. The cubic root of 21616861 is about 278.5677758264.

The spelling of 21616861 in words is "twenty-one million, six hundred sixteen thousand, eight hundred sixty-one".