21421153 has 4 divisors (see below), whose sum is σ = 23068948. Its totient is φ = 19773360.

The previous prime is 21421133. The next prime is 21421159. The reversal of 21421153 is 35112412.

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 4717584 + 16703569 = 2172^2 + 4087^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21421153 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21421153.

It is not an unprimeable number, because it can be changed into a prime (21421159) 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, 823878 + ... + 823903.

It is an arithmetic number, because the mean of its divisors is an integer number (5767237).

Almost surely, 2^21421153 is an apocalyptic number.

It is an amenable number.

21421153 is a deficient number, since it is larger than the sum of its proper divisors (1647795).

21421153 is a wasteful number, since it uses less digits than its factorization.

21421153 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1647794.

The product of its digits is 240, while the sum is 19.

The square root of 21421153 is about 4628.2991476351. The cubic root of 21421153 is about 277.7245559486.

Adding to 21421153 its reverse (35112412), we get a palindrome (56533565).

The spelling of 21421153 in words is "twenty-one million, four hundred twenty-one thousand, one hundred fifty-three".