1961246821 has 4 divisors (see below), whose sum is σ = 1998251532. Its totient is φ = 1924242112.

The previous prime is 1961246759. The next prime is 1961246843. The reversal of 1961246821 is 1286421691.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1675264900 + 285981921 = 40930^2 + 16911^2 .

It is a cyclic number.

It is not a de Polignac number, because 1961246821 - 2²³ = 1952858213 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1961246891) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18502276 + ... + 18502381.

It is an arithmetic number, because the mean of its divisors is an integer number (499562883).

Almost surely, 2^1961246821 is an apocalyptic number.

It is an amenable number.

1961246821 is a deficient number, since it is larger than the sum of its proper divisors (37004711).

1961246821 is an equidigital number, since it uses as much as digits as its factorization.

1961246821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37004710.

The product of its digits is 41472, while the sum is 40.

The square root of 1961246821 is about 44285.9664114943. The cubic root of 1961246821 is about 1251.7302590046.

The spelling of 1961246821 in words is "one billion, nine hundred sixty-one million, two hundred forty-six thousand, eight hundred twenty-one".