21157226 has 4 divisors (see below), whose sum is σ = 31735842. Its totient is φ = 10578612.

The previous prime is 21157207. The next prime is 21157243. The reversal of 21157226 is 62275112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 14055001 + 7102225 = 3749^2 + 2665^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21157195 and 21157204.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5289305 + ... + 5289308.

Almost surely, 2^21157226 is an apocalyptic number.

21157226 is a deficient number, since it is larger than the sum of its proper divisors (10578616).

21157226 is a wasteful number, since it uses less digits than its factorization.

21157226 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10578615.

The product of its digits is 1680, while the sum is 26.

The square root of 21157226 is about 4599.6984683781. The cubic root of 21157226 is about 276.5792375477.

The spelling of 21157226 in words is "twenty-one million, one hundred fifty-seven thousand, two hundred twenty-six".