1551635681 has 2 divisors, whose sum is σ = 1551635682. Its totient is φ = 1551635680.

The previous prime is 1551635671. The next prime is 1551635699. The reversal of 1551635681 is 1865361551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 937339456 + 614296225 = 30616^2 + 24785^2 .

It is a cyclic number.

It is not a de Polignac number, because 1551635681 - 2¹⁰ = 1551634657 is a prime.

It is a super-2 number, since 2×1551635681² = 4815146573104667522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1551635671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 775817840 + 775817841.

It is an arithmetic number, because the mean of its divisors is an integer number (775817841).

Almost surely, 2^1551635681 is an apocalyptic number.

It is an amenable number.

1551635681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1551635681 is an equidigital number, since it uses as much as digits as its factorization.

1551635681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108000, while the sum is 41.

The square root of 1551635681 is about 39390.8070620545. The cubic root of 1551635681 is about 1157.7014733257.

The spelling of 1551635681 in words is "one billion, five hundred fifty-one million, six hundred thirty-five thousand, six hundred eighty-one".