1634995981 has 2 divisors, whose sum is σ = 1634995982. Its totient is φ = 1634995980.

The previous prime is 1634995951. The next prime is 1634996039. The reversal of 1634995981 is 1895994361.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1220873481 + 414122500 = 34941^2 + 20350^2 .

It is a cyclic number.

It is not a de Polignac number, because 1634995981 - 2⁷ = 1634995853 is a prime.

It is a super-2 number, since 2×1634995981² = 5346423715772304722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1634995931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 817497990 + 817497991.

It is an arithmetic number, because the mean of its divisors is an integer number (817497991).

Almost surely, 2^1634995981 is an apocalyptic number.

It is an amenable number.

1634995981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1634995981 is an equidigital number, since it uses as much as digits as its factorization.

1634995981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2099520, while the sum is 55.

The square root of 1634995981 is about 40435.0835414000. The cubic root of 1634995981 is about 1178.0730738239.

The spelling of 1634995981 in words is "one billion, six hundred thirty-four million, nine hundred ninety-five thousand, nine hundred eighty-one".