21275157 has 4 divisors (see below), whose sum is σ = 28366880. Its totient is φ = 14183436.

The previous prime is 21275129. The next prime is 21275171. The reversal of 21275157 is 75157212.

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 not a de Polignac number, because 21275157 - 2¹⁰ = 21274133 is a prime.

It is the 4613-rd Hogben number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21275197) by changing a digit.

It is a nontrivial repunit in base 4612.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3545857 + ... + 3545862.

It is an arithmetic number, because the mean of its divisors is an integer number (7091720).

Almost surely, 2^21275157 is an apocalyptic number.

It is an amenable number.

21275157 is a deficient number, since it is larger than the sum of its proper divisors (7091723).

21275157 is an equidigital number, since it uses as much as digits as its factorization.

21275157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7091722.

The product of its digits is 4900, while the sum is 30.

The square root of 21275157 is about 4612.5000813008. The cubic root of 21275157 is about 277.0921726214.

The spelling of 21275157 in words is "twenty-one million, two hundred seventy-five thousand, one hundred fifty-seven".