1557457681 has 8 divisors (see below), whose sum is σ = 1677569600. Its totient is φ = 1437389712.

The previous prime is 1557457667. The next prime is 1557457691. The reversal of 1557457681 is 1867547551.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1557457681 - 2⁷ = 1557457553 is a prime.

It is a super-3 number, since 3×1557457681³ (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1557457621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 125356 + ... + 137218.

It is an arithmetic number, because the mean of its divisors is an integer number (209696200).

Almost surely, 2^1557457681 is an apocalyptic number.

It is an amenable number.

1557457681 is a deficient number, since it is larger than the sum of its proper divisors (120111919).

1557457681 is a wasteful number, since it uses less digits than its factorization.

1557457681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21975.

The product of its digits is 1176000, while the sum is 49.

The square root of 1557457681 is about 39464.6383614496. The cubic root of 1557457681 is about 1159.1476301228.

The spelling of 1557457681 in words is "one billion, five hundred fifty-seven million, four hundred fifty-seven thousand, six hundred eighty-one".