21621059 has 4 divisors (see below), whose sum is σ = 22892904. Its totient is φ = 20349216.

The previous prime is 21621053. The next prime is 21621073. The reversal of 21621059 is 95012612.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21621059 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21621053) 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, 635897 + ... + 635930.

It is an arithmetic number, because the mean of its divisors is an integer number (5723226).

Almost surely, 2^21621059 is an apocalyptic number.

21621059 is a deficient number, since it is larger than the sum of its proper divisors (1271845).

21621059 is a wasteful number, since it uses less digits than its factorization.

21621059 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1271844.

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 21621059 is about 4649.8450511818. The cubic root of 21621059 is about 278.5858073039.

The spelling of 21621059 in words is "twenty-one million, six hundred twenty-one thousand, fifty-nine".