21359421 has 6 divisors (see below), whose sum is σ = 30852510. Its totient is φ = 14239608.

The previous prime is 21359417. The next prime is 21359431. The reversal of 21359421 is 12495312.

It can be written as a sum of positive squares in only one way, i.e., 20602521 + 756900 = 4539^2 + 870^2 .

It is not a de Polignac number, because 21359421 - 2² = 21359417 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21359431) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1186626 + ... + 1186643.

It is an arithmetic number, because the mean of its divisors is an integer number (5142085).

Almost surely, 2^21359421 is an apocalyptic number.

It is an amenable number.

21359421 is a deficient number, since it is larger than the sum of its proper divisors (9493089).

21359421 is a wasteful number, since it uses less digits than its factorization.

21359421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2373275 (or 2373272 counting only the distinct ones).

The product of its digits is 2160, while the sum is 27.

The square root of 21359421 is about 4621.6253634409. The cubic root of 21359421 is about 277.4575148009.

The spelling of 21359421 in words is "twenty-one million, three hundred fifty-nine thousand, four hundred twenty-one".