1917651681 has 27 divisors (see below), whose sum is σ = 3046942353. Its totient is φ = 1161337320.

The previous prime is 1917651649. The next prime is 1917651719. The reversal of 1917651681 is 1861567191.

The square root of 1917651681 is 43791.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 1917651681 - 2⁵ = 1917651649 is a prime.

It is a super-2 number, since 2×1917651681² = 7354775939284251522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1917651641) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1444440 + ... + 1445766.

Almost surely, 2^1917651681 is an apocalyptic number.

1917651681 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1917651681 is the 43791-st square number.

1917651681 is the 21896-th centered octagonal number.

It is an amenable number.

1917651681 is a deficient number, since it is larger than the sum of its proper divisors (1129290672).

1917651681 is an equidigital number, since it uses as much as digits as its factorization.

1917651681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2682 (or 1341 counting only the distinct ones).

The product of its digits is 90720, while the sum is 45.

The cubic root of 1917651681 is about 1242.3860752977.

The spelling of 1917651681 in words is "one billion, nine hundred seventeen million, six hundred fifty-one thousand, six hundred eighty-one".