21168157 has 4 divisors (see below), whose sum is σ = 21202336. Its totient is φ = 21133980.

The previous prime is 21168151. The next prime is 21168209. The reversal of 21168157 is 75186112.

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-21168157 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 (21168151) 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, 16143 + ... + 17404.

It is an arithmetic number, because the mean of its divisors is an integer number (5300584).

Almost surely, 2^21168157 is an apocalyptic number.

It is an amenable number.

21168157 is a deficient number, since it is larger than the sum of its proper divisors (34179).

21168157 is an equidigital number, since it uses as much as digits as its factorization.

21168157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34178.

The product of its digits is 3360, while the sum is 31.

The square root of 21168157 is about 4600.8865450041. The cubic root of 21168157 is about 276.6268614206.

The spelling of 21168157 in words is "twenty-one million, one hundred sixty-eight thousand, one hundred fifty-seven".