1698988981 has 2 divisors, whose sum is σ = 1698988982. Its totient is φ = 1698988980.

The previous prime is 1698988937. The next prime is 1698988997. The reversal of 1698988981 is 1898898961.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1653642225 + 45346756 = 40665^2 + 6734^2 .

It is an emirp because it is prime and its reverse (1898898961) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 1868868691 and 1968688681.

It is a cyclic number.

It is not a de Polignac number, because 1698988981 - 2⁹ = 1698988469 is a prime.

It is a super-2 number, since 2×1698988981² = 5773127115118836722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1698988901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 849494490 + 849494491.

It is an arithmetic number, because the mean of its divisors is an integer number (849494491).

Almost surely, 2^1698988981 is an apocalyptic number.

It is an amenable number.

1698988981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1698988981 is an equidigital number, since it uses as much as digits as its factorization.

1698988981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17915904, while the sum is 67.

The square root of 1698988981 is about 41218.7940265117. The cubic root of 1698988981 is about 1193.2465500716.

The spelling of 1698988981 in words is "one billion, six hundred ninety-eight million, nine hundred eighty-eight thousand, nine hundred eighty-one".