21157641 has 12 divisors (see below), whose sum is σ = 30663360. Its totient is φ = 14057880.

The previous prime is 21157627. The next prime is 21157649. The reversal of 21157641 is 14675112.

It is a happy number.

21157641 is a `hidden beast` number, since 2 + 1 + 15 + 7 + 641 = 666.

It is not a de Polignac number, because 21157641 - 2¹³ = 21149449 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21157649) 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 11 ways as a sum of consecutive naturals, for example, 981 + ... + 6578.

It is an arithmetic number, because the mean of its divisors is an integer number (2555280).

Almost surely, 2^21157641 is an apocalyptic number.

It is an amenable number.

21157641 is a deficient number, since it is larger than the sum of its proper divisors (9505719).

21157641 is a wasteful number, since it uses less digits than its factorization.

21157641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7876 (or 7873 counting only the distinct ones).

The product of its digits is 1680, while the sum is 27.

The square root of 21157641 is about 4599.7435798096. The cubic root of 21157641 is about 276.5810459075.

The spelling of 21157641 in words is "twenty-one million, one hundred fifty-seven thousand, six hundred forty-one".