997021553 has 4 divisors (see below), whose sum is σ = 1087659888. Its totient is φ = 906383220.

The previous prime is 997021513. The next prime is 997021591. The reversal of 997021553 is 355120799.

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: 355120799 = 11 ⋅32283709.

It is a cyclic number.

It is not a de Polignac number, because 997021553 - 2¹⁴ = 997005169 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 997021553.

It is not an unprimeable number, because it can be changed into a prime (997021513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45319151 + ... + 45319172.

It is an arithmetic number, because the mean of its divisors is an integer number (271914972).

Almost surely, 2^997021553 is an apocalyptic number.

It is an amenable number.

997021553 is a deficient number, since it is larger than the sum of its proper divisors (90638335).

997021553 is a wasteful number, since it uses less digits than its factorization.

997021553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90638334.

The product of its (nonzero) digits is 85050, while the sum is 41.

The square root of 997021553 is about 31575.6481010287. The cubic root of 997021553 is about 999.0061970161.

The spelling of 997021553 in words is "nine hundred ninety-seven million, twenty-one thousand, five hundred fifty-three".