21055231 has 8 divisors (see below), whose sum is σ = 23013504. Its totient is φ = 19176960.

The previous prime is 21055217. The next prime is 21055259. The reversal of 21055231 is 13255012.

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 21055231 - 2¹⁹ = 20530943 is a prime.

It is a super-2 number, since 2×21055231² = 886645504926722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21055199 and 21055208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21055261) 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, 19450 + ... + 20503.

It is an arithmetic number, because the mean of its divisors is an integer number (2876688).

Almost surely, 2^21055231 is an apocalyptic number.

21055231 is a deficient number, since it is larger than the sum of its proper divisors (1958273).

21055231 is a wasteful number, since it uses less digits than its factorization.

21055231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40001.

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 21055231 is about 4588.5979340099. The cubic root of 21055231 is about 276.1340759695.

The spelling of 21055231 in words is "twenty-one million, fifty-five thousand, two hundred thirty-one".