1655661681 has 48 divisors (see below), whose sum is σ = 2562318720. Its totient is φ = 1055825280.

The previous prime is 1655661659. The next prime is 1655661703. The reversal of 1655661681 is 1861665561.

1655661681 is a `hidden beast` number, since 1 + 6 + 5 + 566 + 1 + 6 + 81 = 666.

It is an interprime number because it is at equal distance from previous prime (1655661659) and next prime (1655661703).

It is not a de Polignac number, because 1655661681 - 2¹⁷ = 1655530609 is a prime.

It is a super-2 number, since 2×1655661681² = 5482431203863491522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1655661781) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5323516 + ... + 5323826.

It is an arithmetic number, because the mean of its divisors is an integer number (53381640).

Almost surely, 2^1655661681 is an apocalyptic number.

It is an amenable number.

1655661681 is a deficient number, since it is larger than the sum of its proper divisors (906657039).

1655661681 is an equidigital number, since it uses as much as digits as its factorization.

1655661681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 503 (or 424 counting only the distinct ones).

The product of its digits is 259200, while the sum is 45.

The square root of 1655661681 is about 40689.8228184887. The cubic root of 1655661681 is about 1183.0157660207.

The spelling of 1655661681 in words is "one billion, six hundred fifty-five million, six hundred sixty-one thousand, six hundred eighty-one".