988381981 has 2 divisors, whose sum is σ = 988381982. Its totient is φ = 988381980.

The previous prime is 988381951. The next prime is 988381987. The reversal of 988381981 is 189183889.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 905408100 + 82973881 = 30090^2 + 9109^2 .

It is an emirp because it is prime and its reverse (189183889) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-988381981 is a prime.

It is a super-2 number, since 2×988381981² = 1953797880730968722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (988381987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 494190990 + 494190991.

It is an arithmetic number, because the mean of its divisors is an integer number (494190991).

Almost surely, 2^988381981 is an apocalyptic number.

It is an amenable number.

988381981 is a deficient number, since it is larger than the sum of its proper divisors (1).

988381981 is an equidigital number, since it uses as much as digits as its factorization.

988381981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 995328, while the sum is 55.

The square root of 988381981 is about 31438.5429210706. The cubic root of 988381981 is about 996.1122318463.

The spelling of 988381981 in words is "nine hundred eighty-eight million, three hundred eighty-one thousand, nine hundred eighty-one".