1981209902 has 16 divisors (see below), whose sum is σ = 3396940512. Its totient is φ = 848944800.

The previous prime is 1981209863. The next prime is 1981209943. The reversal of 1981209902 is 2099021891.

It is a self number, because there is not a number n which added to its sum of digits gives 1981209902.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 131468 + ... + 145760.

It is an arithmetic number, because the mean of its divisors is an integer number (212308782).

Almost surely, 2^1981209902 is an apocalyptic number.

1981209902 is a deficient number, since it is larger than the sum of its proper divisors (1415730610).

1981209902 is a wasteful number, since it uses less digits than its factorization.

1981209902 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24203.

The product of its (nonzero) digits is 23328, while the sum is 41.

The square root of 1981209902 is about 44510.7841090224. The cubic root of 1981209902 is about 1255.9629550618.

The spelling of 1981209902 in words is "one billion, nine hundred eighty-one million, two hundred nine thousand, nine hundred two".