21618157 has 8 divisors (see below), whose sum is σ = 23617152. Its totient is φ = 19624800.

The previous prime is 21618133. The next prime is 21618197. The reversal of 21618157 is 75181612.

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 21618157 - 2²³ = 13229549 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 (21618127) 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, 13857 + ... + 15337.

It is an arithmetic number, because the mean of its divisors is an integer number (2952144).

Almost surely, 2^21618157 is an apocalyptic number.

It is an amenable number.

21618157 is a deficient number, since it is larger than the sum of its proper divisors (1998995).

21618157 is a wasteful number, since it uses less digits than its factorization.

21618157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2819.

The product of its digits is 3360, while the sum is 31.

The square root of 21618157 is about 4649.5329873010. The cubic root of 21618157 is about 278.5733427250.

Adding to 21618157 its reverse (75181612), we get a palindrome (96799769).

The spelling of 21618157 in words is "twenty-one million, six hundred eighteen thousand, one hundred fifty-seven".