21168457 has 4 divisors (see below), whose sum is σ = 21374080. Its totient is φ = 20962836.

The previous prime is 21168439. The next prime is 21168461. The reversal of 21168457 is 75486112.

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 not a de Polignac number, because 21168457 - 2²³ = 12779849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21160457) 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, 102657 + ... + 102862.

It is an arithmetic number, because the mean of its divisors is an integer number (5343520).

Almost surely, 2^21168457 is an apocalyptic number.

It is an amenable number.

21168457 is a deficient number, since it is larger than the sum of its proper divisors (205623).

21168457 is a wasteful number, since it uses less digits than its factorization.

21168457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 205622.

The product of its digits is 13440, while the sum is 34.

The square root of 21168457 is about 4600.9191473009. The cubic root of 21168457 is about 276.6281682210.

The spelling of 21168457 in words is "twenty-one million, one hundred sixty-eight thousand, four hundred fifty-seven".