1021665500 has 48 divisors (see below), whose sum is σ = 2253521088. Its totient is φ = 404600000.

The previous prime is 1021665499. The next prime is 1021665503. The reversal of 1021665500 is 55661201.

It is a self number, because there is not a number n which added to its sum of digits gives 1021665500.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1021665503) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 40385 + ... + 60615.

It is an arithmetic number, because the mean of its divisors is an integer number (46948356).

Almost surely, 2^1021665500 is an apocalyptic number.

1021665500 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1021665500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1126760544).

1021665500 is an abundant number, since it is smaller than the sum of its proper divisors (1231855588).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1021665500 is a wasteful number, since it uses less digits than its factorization.

1021665500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20351 (or 20339 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 1021665500 is about 31963.5026240867. The cubic root of 1021665500 is about 1007.1702972876.

The spelling of 1021665500 in words is "one billion, twenty-one million, six hundred sixty-five thousand, five hundred".