821610981 has 24 divisors (see below), whose sum is σ = 1205360000. Its totient is φ = 539203392.

The previous prime is 821610961. The next prime is 821610983. The reversal of 821610981 is 189016128.

It is not a de Polignac number, because 821610981 - 2⁶ = 821610917 is a prime.

It is a super-2 number, since 2×821610981² = 1350089208199564722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821610983) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 267945 + ... + 270993.

Almost surely, 2^821610981 is an apocalyptic number.

It is an amenable number.

821610981 is a deficient number, since it is larger than the sum of its proper divisors (383749019).

821610981 is a wasteful number, since it uses less digits than its factorization.

821610981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3513 (or 3510 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 36.

The square root of 821610981 is about 28663.7572729048. The cubic root of 821610981 is about 936.6027135294.

The spelling of 821610981 in words is "eight hundred twenty-one million, six hundred ten thousand, nine hundred eighty-one".