21282157 has 8 divisors (see below), whose sum is σ = 23478840. Its totient is φ = 19165440.

The previous prime is 21282139. The next prime is 21282167. The reversal of 21282157 is 75128212.

It can be written as a sum of positive squares in 4 ways, for example, as 978121 + 20304036 = 989^2 + 4506^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21282157 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 (21282127) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19432 + ... + 20497.

It is an arithmetic number, because the mean of its divisors is an integer number (2934855).

Almost surely, 2^21282157 is an apocalyptic number.

It is an amenable number.

21282157 is a deficient number, since it is larger than the sum of its proper divisors (2196683).

21282157 is a wasteful number, since it uses less digits than its factorization.

21282157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39983.

The product of its digits is 2240, while the sum is 28.

The square root of 21282157 is about 4613.2588264696. The cubic root of 21282157 is about 277.1225591190.

It can be divided in two parts, 212821 and 57, that added together give a triangular number (212878 = T₆₅₂).

The spelling of 21282157 in words is "twenty-one million, two hundred eighty-two thousand, one hundred fifty-seven".