1981390968 has 24 divisors (see below), whose sum is σ = 5366267400. Its totient is φ = 660463632.

The previous prime is 1981390963. The next prime is 1981390981. The reversal of 1981390968 is 8690931891.

1981390968 is a `hidden beast` number, since 198 + 1 + 390 + 9 + 68 = 666.

It is a tau number, because it is divible by the number of its divisors (24).

It is a super-3 number, since 3×1981390968³ (a number of 29 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981390963) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 13759588 + ... + 13759731.

It is an arithmetic number, because the mean of its divisors is an integer number (223594475).

Almost surely, 2^1981390968 is an apocalyptic number.

1981390968 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

1981390968 is an abundant number, since it is smaller than the sum of its proper divisors (3384876432).

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

1981390968 is a wasteful number, since it uses less digits than its factorization.

1981390968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27519331 (or 27519324 counting only the distinct ones).

The product of its (nonzero) digits is 839808, while the sum is 54.

The square root of 1981390968 is about 44512.8180190830. The cubic root of 1981390968 is about 1256.0012153963.

The spelling of 1981390968 in words is "one billion, nine hundred eighty-one million, three hundred ninety thousand, nine hundred sixty-eight".