1906697981 has 2 divisors, whose sum is σ = 1906697982. Its totient is φ = 1906697980.

The previous prime is 1906697941. The next prime is 1906698037. The reversal of 1906697981 is 1897966091.

It is an a-pointer prime, because the next prime (1906698037) can be obtained adding 1906697981 to its sum of digits (56).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1477172356 + 429525625 = 38434^2 + 20725^2 .

It is a cyclic number.

It is not a de Polignac number, because 1906697981 - 2¹⁸ = 1906435837 is a prime.

It is a super-2 number, since 2×1906697981² = 7270994381498952722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1906697941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 953348990 + 953348991.

It is an arithmetic number, because the mean of its divisors is an integer number (953348991).

Almost surely, 2^1906697981 is an apocalyptic number.

It is an amenable number.

1906697981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1906697981 is an equidigital number, since it uses as much as digits as its factorization.

1906697981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1469664, while the sum is 56.

The square root of 1906697981 is about 43665.7529535447. The cubic root of 1906697981 is about 1240.0160379906.

The spelling of 1906697981 in words is "one billion, nine hundred six million, six hundred ninety-seven thousand, nine hundred eighty-one".