1378521540 has 216 divisors, whose sum is σ = 4635933120. Its totient is φ = 331309440.

The previous prime is 1378521511. The next prime is 1378521569. The reversal of 1378521540 is 451258731.

1378521540 is a `hidden beast` number, since 1 + 37 + 85 + 2 + 1 + 540 = 666.

It is an interprime number because it is at equal distance from previous prime (1378521511) and next prime (1378521569).

It is a super-4 number, since 4×1378521540⁴ (a number of 38 digits) contains 4444 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1378521495 and 1378521504.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 3637071 + ... + 3637449.

Almost surely, 2^1378521540 is an apocalyptic number.

1378521540 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 1378521540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2317966560).

1378521540 is an abundant number, since it is smaller than the sum of its proper divisors (3257411580).

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

1378521540 is a wasteful number, since it uses less digits than its factorization.

1378521540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 583 (or 567 counting only the distinct ones).

The product of its (nonzero) digits is 33600, while the sum is 36.

The square root of 1378521540 is about 37128.4465066881. The cubic root of 1378521540 is about 1112.9385493156.

The spelling of 1378521540 in words is "one billion, three hundred seventy-eight million, five hundred twenty-one thousand, five hundred forty".