1020021661656 has 96 divisors (see below), whose sum is σ = 2839150314000. Its totient is φ = 330649627392.

The previous prime is 1020021661627. The next prime is 1020021661727. The reversal of 1020021661656 is 6561661200201.

1020021661656 is a `hidden beast` number, since 1 + 0 + 20 + 0 + 2 + 16 + 616 + 5 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 1020021661656.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10371 + ... + 1428338.

Almost surely, 2^{1020021661656} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1020021661656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1419575157000).

1020021661656 is an abundant number, since it is smaller than the sum of its proper divisors (1819128652344).

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

1020021661656 is a wasteful number, since it uses less digits than its factorization.

1020021661656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1438993 (or 1438986 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

Adding to 1020021661656 its reverse (6561661200201), we get a palindrome (7581682861857).

The spelling of 1020021661656 in words is "one trillion, twenty billion, twenty-one million, six hundred sixty-one thousand, six hundred fifty-six".