1217981520 has 120 divisors (see below), whose sum is σ = 4674748416. Its totient is φ = 278394624.

The previous prime is 1217981497. The next prime is 1217981533. The reversal of 1217981520 is 251897121.

It is a happy number.

1217981520 is a `hidden beast` number, since 121 + 7 + 9 + 8 + 1 + 520 = 666.

It is a tau number, because it is divible by the number of its divisors (120).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 115792 + ... + 125871.

Almost surely, 2^1217981520 is an apocalyptic number.

1217981520 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1217981520 is an abundant number, since it is smaller than the sum of its proper divisors (3456766896).

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

1217981520 is a wasteful number, since it uses less digits than its factorization.

1217981520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 241689 (or 241680 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 36.

The square root of 1217981520 is about 34899.5919746922. The cubic root of 1217981520 is about 1067.9401136306.

The spelling of 1217981520 in words is "one billion, two hundred seventeen million, nine hundred eighty-one thousand, five hundred twenty".