21612655 has 8 divisors (see below), whose sum is σ = 25960752. Its totient is φ = 17273088.

The previous prime is 21612637. The next prime is 21612677. The reversal of 21612655 is 55621612.

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

It is a cyclic number.

It is not a de Polignac number, because 21612655 - 2⁵ = 21612623 is a prime.

It is a super-2 number, since 2×21612655² = 934213712298050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 7039 + ... + 9631.

It is an arithmetic number, because the mean of its divisors is an integer number (3245094).

Almost surely, 2^21612655 is an apocalyptic number.

21612655 is a deficient number, since it is larger than the sum of its proper divisors (4348097).

21612655 is a wasteful number, since it uses less digits than its factorization.

21612655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4265.

The product of its digits is 3600, while the sum is 28.

The square root of 21612655 is about 4648.9412773233. The cubic root of 21612655 is about 278.5497076455.

The spelling of 21612655 in words is "twenty-one million, six hundred twelve thousand, six hundred fifty-five".