21680157 has 8 divisors (see below), whose sum is σ = 28929376. Its totient is φ = 14442192.

The previous prime is 21680149. The next prime is 21680167. The reversal of 21680157 is 75108612.

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

It is not a de Polignac number, because 21680157 - 2³ = 21680149 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 (21680167) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4143 + ... + 7779.

It is an arithmetic number, because the mean of its divisors is an integer number (3616172).

Almost surely, 2^21680157 is an apocalyptic number.

It is an amenable number.

21680157 is a deficient number, since it is larger than the sum of its proper divisors (7249219).

21680157 is a wasteful number, since it uses less digits than its factorization.

21680157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5627.

The product of its (nonzero) digits is 3360, while the sum is 30.

The square root of 21680157 is about 4656.1955500172. The cubic root of 21680157 is about 278.8394008992.

Adding to 21680157 its reverse (75108612), we get a palindrome (96788769).

The spelling of 21680157 in words is "twenty-one million, six hundred eighty thousand, one hundred fifty-seven".