821501231 has 2 divisors, whose sum is σ = 821501232. Its totient is φ = 821501230.

The previous prime is 821501207. The next prime is 821501237. The reversal of 821501231 is 132105128.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 821501231 - 2²² = 817306927 is a prime.

It is a super-2 number, since 2×821501231² = 1349728545069030722, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 821501197 and 821501206.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (821501237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410750615 + 410750616.

It is an arithmetic number, because the mean of its divisors is an integer number (410750616).

Almost surely, 2^821501231 is an apocalyptic number.

821501231 is a deficient number, since it is larger than the sum of its proper divisors (1).

821501231 is an equidigital number, since it uses as much as digits as its factorization.

821501231 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 480, while the sum is 23.

The square root of 821501231 is about 28661.8427704849. The cubic root of 821501231 is about 936.5610081776.

Adding to 821501231 its reverse (132105128), we get a palindrome (953606359).

The spelling of 821501231 in words is "eight hundred twenty-one million, five hundred one thousand, two hundred thirty-one".