1021645655 has 4 divisors (see below), whose sum is σ = 1225974792. Its totient is φ = 817316520.

The previous prime is 1021645633. The next prime is 1021645661. The reversal of 1021645655 is 5565461201.

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

It is not a de Polignac number, because 1021645655 - 2¹² = 1021641559 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 102164561 + ... + 102164570.

It is an arithmetic number, because the mean of its divisors is an integer number (306493698).

Almost surely, 2^1021645655 is an apocalyptic number.

1021645655 is a deficient number, since it is larger than the sum of its proper divisors (204329137).

1021645655 is an equidigital number, since it uses as much as digits as its factorization.

1021645655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204329136.

The product of its (nonzero) digits is 36000, while the sum is 35.

The square root of 1021645655 is about 31963.1921903930. The cubic root of 1021645655 is about 1007.1637760978.

The spelling of 1021645655 in words is "one billion, twenty-one million, six hundred forty-five thousand, six hundred fifty-five".