1553857561 has 3 divisors (see below), whose sum is σ = 1553896981. Its totient is φ = 1553818142.

The previous prime is 1553857559. The next prime is 1553857597. The reversal of 1553857561 is 1657583551.

The square root of 1553857561 is 39419.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 1553857561 - 2¹ = 1553857559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1553858561) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 19710 + ... + 59128.

Almost surely, 2^1553857561 is an apocalyptic number.

1553857561 is the 39419-th square number.

1553857561 is the 19710-th centered octagonal number.

It is an amenable number.

1553857561 is a deficient number, since it is larger than the sum of its proper divisors (39420).

1553857561 is an frugal number, since it uses more digits than its factorization.

1553857561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78838 (or 39419 counting only the distinct ones).

The product of its digits is 630000, while the sum is 46.

The cubic root of 1553857561 is about 1158.2538037813.

The spelling of 1553857561 in words is "one billion, five hundred fifty-three million, eight hundred fifty-seven thousand, five hundred sixty-one".