961821 has 24 divisors (see below), whose sum is σ = 1659840. Its totient is φ = 548856.

The previous prime is 961817. The next prime is 961841. The reversal of 961821 is 128169.

It is not a de Polignac number, because 961821 - 2² = 961817 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

961821 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (961811) 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, 960 + ... + 1686.

It is an arithmetic number, because the mean of its divisors is an integer number (69160).

2⁹⁶¹⁸²¹ is an apocalyptic number.

It is an amenable number.

961821 is a deficient number, since it is larger than the sum of its proper divisors (698019).

961821 is a wasteful number, since it uses less digits than its factorization.

961821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 750 (or 737 counting only the distinct ones).

The product of its digits is 864, while the sum is 27.

The square root of 961821 is about 980.7247320222. The cubic root of 961821 is about 98.7108181895.

The spelling of 961821 in words is "nine hundred sixty-one thousand, eight hundred twenty-one".