1291521420 has 216 divisors, whose sum is σ = 4597092864. Its totient is φ = 292626432.

The previous prime is 1291521403. The next prime is 1291521499. The reversal of 1291521420 is 241251921.

1291521420 is a `hidden beast` number, since 12 + 91 + 521 + 42 + 0 = 666.

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, 1119564 + ... + 1120716.

Almost surely, 2^1291521420 is an apocalyptic number.

1291521420 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 1291521420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2298546432).

1291521420 is an abundant number, since it is smaller than the sum of its proper divisors (3305571444).

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

1291521420 is a wasteful number, since it uses less digits than its factorization.

1291521420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1309 (or 1297 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 1291521420 is about 35937.7436687391. The cubic root of 1291521420 is about 1089.0150235591.

The spelling of 1291521420 in words is "one billion, two hundred ninety-one million, five hundred twenty-one thousand, four hundred twenty".