981561421 has 4 divisors (see below), whose sum is σ = 981726012. Its totient is φ = 981396832.

The previous prime is 981561407. The next prime is 981561433. The reversal of 981561421 is 124165189.

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 741745225 + 239816196 = 27235^2 + 15486^2 .

It is a cyclic number.

It is not a de Polignac number, because 981561421 - 2⁷ = 981561293 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (981561461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 73000 + ... + 85393.

It is an arithmetic number, because the mean of its divisors is an integer number (245431503).

Almost surely, 2^981561421 is an apocalyptic number.

It is an amenable number.

981561421 is a deficient number, since it is larger than the sum of its proper divisors (164591).

981561421 is a wasteful number, since it uses less digits than its factorization.

981561421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164590.

The product of its digits is 17280, while the sum is 37.

The square root of 981561421 is about 31329.8806413303. The cubic root of 981561421 is about 993.8156395286.

The spelling of 981561421 in words is "nine hundred eighty-one million, five hundred sixty-one thousand, four hundred twenty-one".