1287990 has 48 divisors (see below), whose sum is σ = 3656016. Its totient is φ = 312000.

The previous prime is 1287989. The next prime is 1287997. The reversal of 1287990 is 997821.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1287997) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 340 + ... + 1640.

It is an arithmetic number, because the mean of its divisors is an integer number (76167).

2^1287990 is an apocalyptic number.

1287990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1287990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1828008).

1287990 is an abundant number, since it is smaller than the sum of its proper divisors (2368026).

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

1287990 is a wasteful number, since it uses less digits than its factorization.

1287990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1325 (or 1322 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 1287990 is about 1134.8964710492. The cubic root of 1287990 is about 108.8021549278.

It can be divided in two parts, 128 and 7990, that added together give a palindrome (8118).

The spelling of 1287990 in words is "one million, two hundred eighty-seven thousand, nine hundred ninety".