821001261 has 16 divisors (see below), whose sum is σ = 1170126720. Its totient is φ = 510766080.

The previous prime is 821001253. The next prime is 821001287. The reversal of 821001261 is 162100128.

It is not a de Polignac number, because 821001261 - 2³ = 821001253 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821001061) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 142276 + ... + 147933.

It is an arithmetic number, because the mean of its divisors is an integer number (73132920).

Almost surely, 2^821001261 is an apocalyptic number.

It is an amenable number.

821001261 is a deficient number, since it is larger than the sum of its proper divisors (349125459).

821001261 is a wasteful number, since it uses less digits than its factorization.

821001261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 290276.

The product of its (nonzero) digits is 192, while the sum is 21.

The square root of 821001261 is about 28653.1195683821. The cubic root of 821001261 is about 936.3709709566.

Adding to 821001261 its reverse (162100128), we get a palindrome (983101389).

The spelling of 821001261 in words is "eight hundred twenty-one million, one thousand, two hundred sixty-one".