21221065157 has 4 divisors (see below), whose sum is σ = 21222542880. Its totient is φ = 21219587436.

The previous prime is 21221065079. The next prime is 21221065163. The reversal of 21221065157 is 75156012212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21221065157 - 2⁸ = 21221064901 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 (21221065757) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 717107 + ... + 746112.

It is an arithmetic number, because the mean of its divisors is an integer number (5305635720).

Almost surely, 2^21221065157 is an apocalyptic number.

It is an amenable number.

21221065157 is a deficient number, since it is larger than the sum of its proper divisors (1477723).

21221065157 is a wasteful number, since it uses less digits than its factorization.

21221065157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1477722.

The product of its (nonzero) digits is 8400, while the sum is 32.

Adding to 21221065157 its reverse (75156012212), we get a palindrome (96377077369).

The spelling of 21221065157 in words is "twenty-one billion, two hundred twenty-one million, sixty-five thousand, one hundred fifty-seven".