1557421506 has 48 divisors (see below), whose sum is σ = 3504822048. Its totient is φ = 518335200.

The previous prime is 1557421477. The next prime is 1557421529. The reversal of 1557421506 is 6051247551.

1557421506 is a `hidden beast` number, since 15 + 574 + 21 + 50 + 6 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 367741 + ... + 371951.

It is an arithmetic number, because the mean of its divisors is an integer number (73017126).

Almost surely, 2^1557421506 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1557421506, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1752411024).

1557421506 is an abundant number, since it is smaller than the sum of its proper divisors (1947400542).

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

1557421506 is an equidigital number, since it uses as much as digits as its factorization.

1557421506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4989 (or 4977 counting only the distinct ones).

The product of its (nonzero) digits is 42000, while the sum is 36.

The square root of 1557421506 is about 39464.1800370919. The cubic root of 1557421506 is about 1159.1386555632.

The spelling of 1557421506 in words is "one billion, five hundred fifty-seven million, four hundred twenty-one thousand, five hundred six".