1387820 has 48 divisors (see below), whose sum is σ = 3483648. Its totient is φ = 454080.

The previous prime is 1387819. The next prime is 1387823. The reversal of 1387820 is 287831.

1387820 = 413² + 414² + ... + 420².

It is a Smith number, since the sum of its digits (29) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (1387823) 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, 3005 + ... + 3435.

It is an arithmetic number, because the mean of its divisors is an integer number (72576).

2^1387820 is an apocalyptic number.

1387820 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 1387820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1741824).

1387820 is an abundant number, since it is smaller than the sum of its proper divisors (2095828).

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

1387820 is a wasteful number, since it uses less digits than its factorization.

1387820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 470 (or 468 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 1387820 is about 1178.0577235433. The cubic root of 1387820 is about 111.5435290237.

The spelling of 1387820 in words is "one million, three hundred eighty-seven thousand, eight hundred twenty".