997289021 has 4 divisors (see below), whose sum is σ = 997403772. Its totient is φ = 997174272.

The previous prime is 997288991. The next prime is 997289023. The reversal of 997289021 is 120982799.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 120982799 = 7 ⋅17283257.

It can be written as a sum of positive squares in 2 ways, for example, as 783720025 + 213568996 = 27995^2 + 14614^2 .

It is a cyclic number.

It is not a de Polignac number, because 997289021 - 2¹⁰ = 997287997 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 (997289023) 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, 43166 + ... + 62111.

It is an arithmetic number, because the mean of its divisors is an integer number (249350943).

Almost surely, 2^997289021 is an apocalyptic number.

It is an amenable number.

997289021 is a deficient number, since it is larger than the sum of its proper divisors (114751).

997289021 is a wasteful number, since it uses less digits than its factorization.

997289021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114750.

The product of its (nonzero) digits is 163296, while the sum is 47.

The square root of 997289021 is about 31579.8831695116. The cubic root of 997289021 is about 999.0955225004.

The spelling of 997289021 in words is "nine hundred ninety-seven million, two hundred eighty-nine thousand, twenty-one".