21659051 has 4 divisors (see below), whose sum is σ = 21675000. Its totient is φ = 21643104.

The previous prime is 21659017. The next prime is 21659059. The reversal of 21659051 is 15095612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21659051 - 2¹⁰ = 21658027 is a prime.

It is a super-2 number, since 2×21659051² = 938228980441202, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21659059) 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, 5726 + ... + 8723.

It is an arithmetic number, because the mean of its divisors is an integer number (5418750).

Almost surely, 2^21659051 is an apocalyptic number.

21659051 is a deficient number, since it is larger than the sum of its proper divisors (15949).

21659051 is a wasteful number, since it uses less digits than its factorization.

21659051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15948.

The product of its (nonzero) digits is 2700, while the sum is 29.

The square root of 21659051 is about 4653.9285555324. The cubic root of 21659051 is about 278.7488865607.

The spelling of 21659051 in words is "twenty-one million, six hundred fifty-nine thousand, fifty-one".