21539153 has 4 divisors (see below), whose sum is σ = 22806180. Its totient is φ = 20272128.

The previous prime is 21539149. The next prime is 21539183. The reversal of 21539153 is 35193512.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8456464 + 13082689 = 2908^2 + 3617^2 .

It is a cyclic number.

It is not a de Polignac number, because 21539153 - 2² = 21539149 is a prime.

It is a super-2 number, since 2×21539153² = 927870223914818, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21539183) 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, 633488 + ... + 633521.

It is an arithmetic number, because the mean of its divisors is an integer number (5701545).

Almost surely, 2^21539153 is an apocalyptic number.

It is an amenable number.

21539153 is a deficient number, since it is larger than the sum of its proper divisors (1267027).

21539153 is a wasteful number, since it uses less digits than its factorization.

21539153 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1267026.

The product of its digits is 4050, while the sum is 29.

The square root of 21539153 is about 4641.0293039368. The cubic root of 21539153 is about 278.2335778229.

The spelling of 21539153 in words is "twenty-one million, five hundred thirty-nine thousand, one hundred fifty-three".