21157066 has 48 divisors (see below), whose sum is σ = 39697920. Its totient is φ = 8265600.

The previous prime is 21157049. The next prime is 21157067. The reversal of 21157066 is 66075112.

It is not an unprimeable number, because it can be changed into a prime (21157067) 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 23 ways as a sum of consecutive naturals, for example, 516006 + ... + 516046.

It is an arithmetic number, because the mean of its divisors is an integer number (827040).

Almost surely, 2^21157066 is an apocalyptic number.

21157066 is a deficient number, since it is larger than the sum of its proper divisors (18540854).

21157066 is a wasteful number, since it uses less digits than its factorization.

21157066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151 (or 110 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21157066 is about 4599.6810759008. The cubic root of 21157066 is about 276.5785403424.

It can be divided in two parts, 2 and 1157066, that multiplied together give a palindrome (2314132).

The spelling of 21157066 in words is "twenty-one million, one hundred fifty-seven thousand, sixty-six".