821720151 has 72 divisors (see below), whose sum is σ = 1462734000. Its totient is φ = 441987840.

The previous prime is 821720111. The next prime is 821720171. The reversal of 821720151 is 151027128.

It is not a de Polignac number, because 821720151 - 2¹⁰ = 821719127 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821720111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 2354325 + ... + 2354673.

It is an arithmetic number, because the mean of its divisors is an integer number (20315750).

Almost surely, 2^821720151 is an apocalyptic number.

821720151 is a deficient number, since it is larger than the sum of its proper divisors (641013849).

821720151 is a wasteful number, since it uses less digits than its factorization.

821720151 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 669 (or 659 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 27.

The square root of 821720151 is about 28665.6615308281. The cubic root of 821720151 is about 936.6441947950.

Adding to 821720151 its reverse (151027128), we get a palindrome (972747279).

The spelling of 821720151 in words is "eight hundred twenty-one million, seven hundred twenty thousand, one hundred fifty-one".