21453157 has 4 divisors (see below), whose sum is σ = 23403456. Its totient is φ = 19502860.

The previous prime is 21453143. The next prime is 21453191. The reversal of 21453157 is 75135412.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21453157 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21454157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 975133 + ... + 975154.

It is an arithmetic number, because the mean of its divisors is an integer number (5850864).

Almost surely, 2^21453157 is an apocalyptic number.

It is an amenable number.

21453157 is a deficient number, since it is larger than the sum of its proper divisors (1950299).

21453157 is a wasteful number, since it uses less digits than its factorization.

21453157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1950298.

The product of its digits is 4200, while the sum is 28.

The square root of 21453157 is about 4631.7552828275. The cubic root of 21453157 is about 277.8627974005.

Adding to 21453157 its reverse (75135412), we get a palindrome (96588569).

The spelling of 21453157 in words is "twenty-one million, four hundred fifty-three thousand, one hundred fifty-seven".