2001217556 has 18 divisors (see below), whose sum is σ = 3792249342. Its totient is φ = 923638560.

The previous prime is 2001217507. The next prime is 2001217567. The reversal of 2001217556 is 6557121002.

It can be written as a sum of positive squares in 3 ways, for example, as 63457156 + 1937760400 = 7966^2 + 44020^2 .

It is a super-2 number, since 2×2001217556² = 8009743412885226272, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1479515 + ... + 1480866.

It is an arithmetic number, because the mean of its divisors is an integer number (210680519).

Almost surely, 2^2001217556 is an apocalyptic number.

2001217556 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

2001217556 is a deficient number, since it is larger than the sum of its proper divisors (1791031786).

2001217556 is a wasteful number, since it uses less digits than its factorization.

2001217556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2960411 (or 2960396 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 29.

The square root of 2001217556 is about 44734.9701687617. The cubic root of 2001217556 is about 1260.1766687691.

Adding to 2001217556 its reverse (6557121002), we get a palindrome (8558338558).

The spelling of 2001217556 in words is "two billion, one million, two hundred seventeen thousand, five hundred fifty-six".