1981091892 has 24 divisors (see below), whose sum is σ = 4978128736. Its totient is φ = 609566688.

The previous prime is 1981091881. The next prime is 1981091897. The reversal of 1981091892 is 2981901891.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981091897) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6349498 + ... + 6349809.

Almost surely, 2^1981091892 is an apocalyptic number.

1981091892 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

1981091892 is an abundant number, since it is smaller than the sum of its proper divisors (2997036844).

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

1981091892 is a wasteful number, since it uses less digits than its factorization.

1981091892 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12699327 (or 12699325 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 48.

The square root of 1981091892 is about 44509.4584554789. The cubic root of 1981091892 is about 1255.9380175844.

The spelling of 1981091892 in words is "one billion, nine hundred eighty-one million, ninety-one thousand, eight hundred ninety-two".