It is an Ulam number.
It is a congruent number.
It is an unprimeable number.
21387540 is an apocalyptic number.
1387540 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 1387540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1959552).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
1387540 is a wasteful number, since it uses less digits than its factorization.
1387540 is an evil number, because the sum of its binary digits is even.
The square root of 1387540 is about 1177.9388778710. The cubic root of 1387540 is about 111.5360270209.
The spelling of 1387540 in words is "one million, three hundred eighty-seven thousand, five hundred forty".