1557778420 has 48 divisors (see below), whose sum is σ = 3584564928. Its totient is φ = 563951360.

The previous prime is 1557778381. The next prime is 1557778423. The reversal of 1557778420 is 248777551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1557778423) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34344 + ... + 65536.

It is an arithmetic number, because the mean of its divisors is an integer number (74678436).

Almost surely, 2^1557778420 is an apocalyptic number.

1557778420 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1557778420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1792282464).

1557778420 is an abundant number, since it is smaller than the sum of its proper divisors (2026786508).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1557778420 is a wasteful number, since it uses less digits than its factorization.

1557778420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31440 (or 31438 counting only the distinct ones).

The product of its (nonzero) digits is 548800, while the sum is 46.

The square root of 1557778420 is about 39468.7017774844. The cubic root of 1557778420 is about 1159.2271953308.

It can be divided in two parts, 1557 and 778420, that added together give a palindrome (779977).

The spelling of 1557778420 in words is "one billion, five hundred fifty-seven million, seven hundred seventy-eight thousand, four hundred twenty".