961320821 has 4 divisors (see below), whose sum is σ = 961526592. Its totient is φ = 961115052.

The previous prime is 961320799. The next prime is 961320823. The reversal of 961320821 is 128023169.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 128023169 = 43 ⋅2977283.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-961320821 is a prime.

It is a super-2 number, since 2×961320821² = 1848275441776228082, 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 (961320823) 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 3 ways as a sum of consecutive naturals, for example, 95711 + ... + 105276.

It is an arithmetic number, because the mean of its divisors is an integer number (240381648).

Almost surely, 2^961320821 is an apocalyptic number.

It is an amenable number.

961320821 is a deficient number, since it is larger than the sum of its proper divisors (205771).

961320821 is a wasteful number, since it uses less digits than its factorization.

961320821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205770.

The product of its (nonzero) digits is 5184, while the sum is 32.

The square root of 961320821 is about 31005.1741004627. The cubic root of 961320821 is about 986.9370424994.

The spelling of 961320821 in words is "nine hundred sixty-one million, three hundred twenty thousand, eight hundred twenty-one".