21871157 has 8 divisors (see below), whose sum is σ = 27268032. Its totient is φ = 17042400.

The previous prime is 21871153. The next prime is 21871159. The reversal of 21871157 is 75117812.

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 21871157 - 2² = 21871153 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21871153) 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, 141944 + ... + 142097.

It is an arithmetic number, because the mean of its divisors is an integer number (3408504).

Almost surely, 2^21871157 is an apocalyptic number.

It is an amenable number.

21871157 is a deficient number, since it is larger than the sum of its proper divisors (5396875).

21871157 is a wasteful number, since it uses less digits than its factorization.

21871157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 284059.

The product of its digits is 3920, while the sum is 32.

The square root of 21871157 is about 4676.6608814409. The cubic root of 21871157 is about 279.6558569551.

Adding to 21871157 its reverse (75117812), we get a palindrome (96988969).

It can be divided in two parts, 21 and 871157, that added together give a palindrome (871178).

The spelling of 21871157 in words is "twenty-one million, eight hundred seventy-one thousand, one hundred fifty-seven".