21823157 has 8 divisors (see below), whose sum is σ = 22204056. Its totient is φ = 21445632.

The previous prime is 21823147. The next prime is 21823169. The reversal of 21823157 is 75132812.

It can be written as a sum of positive squares in 4 ways, for example, as 3964081 + 17859076 = 1991^2 + 4226^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21823157 - 2⁸ = 21822901 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 (21823117) 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, 14513 + ... + 15945.

It is an arithmetic number, because the mean of its divisors is an integer number (2775507).

Almost surely, 2^21823157 is an apocalyptic number.

It is an amenable number.

21823157 is a deficient number, since it is larger than the sum of its proper divisors (380899).

21823157 is a wasteful number, since it uses less digits than its factorization.

21823157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1687.

The product of its digits is 3360, while the sum is 29.

The square root of 21823157 is about 4671.5261960092. The cubic root of 21823157 is about 279.4511228820.

Adding to 21823157 its reverse (75132812), we get a palindrome (96955969).

The spelling of 21823157 in words is "twenty-one million, eight hundred twenty-three thousand, one hundred fifty-seven".