21239455 has 12 divisors (see below), whose sum is σ = 26401752. Its totient is φ = 16402400.

The previous prime is 21239453. The next prime is 21239459. The reversal of 21239455 is 55493212.

It is not a de Polignac number, because 21239455 - 2¹ = 21239453 is a prime.

It is a super-2 number, since 2×21239455² = 902228897394050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21239453) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1680 + ... + 6730.

It is an arithmetic number, because the mean of its divisors is an integer number (2200146).

Almost surely, 2^21239455 is an apocalyptic number.

21239455 is a deficient number, since it is larger than the sum of its proper divisors (5162297).

21239455 is an equidigital number, since it uses as much as digits as its factorization.

21239455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5114 (or 5085 counting only the distinct ones).

The product of its digits is 10800, while the sum is 31.

The square root of 21239455 is about 4608.6283208781. The cubic root of 21239455 is about 276.9370890247.

The spelling of 21239455 in words is "twenty-one million, two hundred thirty-nine thousand, four hundred fifty-five".