1021638194 has 4 divisors (see below), whose sum is σ = 1532457294. Its totient is φ = 510819096.

The previous prime is 1021638193. The next prime is 1021638199. The reversal of 1021638194 is 4918361201.

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

It can be written as a sum of positive squares in only one way, i.e., 993069169 + 28569025 = 31513^2 + 5345^2 .

It is not an unprimeable number, because it can be changed into a prime (1021638193) 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 as a sum of consecutive naturals, namely, 255409547 + ... + 255409550.

Almost surely, 2^1021638194 is an apocalyptic number.

1021638194 is a deficient number, since it is larger than the sum of its proper divisors (510819100).

1021638194 is an equidigital number, since it uses as much as digits as its factorization.

1021638194 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 510819099.

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 1021638194 is about 31963.0754778072. The cubic root of 1021638194 is about 1007.1613243452.

Adding to 1021638194 its reverse (4918361201), we get a palindrome (5939999395).

The spelling of 1021638194 in words is "one billion, twenty-one million, six hundred thirty-eight thousand, one hundred ninety-four".