1981218064 has 20 divisors (see below), whose sum is σ = 4386983104. Its totient is φ = 849093408.

The previous prime is 1981218061. The next prime is 1981218067. The reversal of 1981218064 is 4608121891.

It is an interprime number because it is at equal distance from previous prime (1981218061) and next prime (1981218067).

It is a super-3 number, since 3×1981218064³ (a number of 29 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (1981218061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8844612 + ... + 8844835.

Almost surely, 2^1981218064 is an apocalyptic number.

1981218064 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

1981218064 is an abundant number, since it is smaller than the sum of its proper divisors (2405765040).

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

1981218064 is a wasteful number, since it uses less digits than its factorization.

1981218064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17689462 (or 17689456 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 40.

The square root of 1981218064 is about 44510.8757945741. The cubic root of 1981218064 is about 1255.9646797916.

The spelling of 1981218064 in words is "one billion, nine hundred eighty-one million, two hundred eighteen thousand, sixty-four".