1972778691 has 16 divisors (see below), whose sum is σ = 2909269664. Its totient is φ = 1181205504.

The previous prime is 1972778663. The next prime is 1972778707. The reversal of 1972778691 is 1968772791.

It is not a de Polignac number, because 1972778691 - 2⁵ = 1972778659 is a prime.

It is a super-3 number, since 3×1972778691³ (a number of 29 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1972798691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 682126 + ... + 685011.

It is an arithmetic number, because the mean of its divisors is an integer number (181829354).

Almost surely, 2^1972778691 is an apocalyptic number.

1972778691 is a deficient number, since it is larger than the sum of its proper divisors (936490973).

1972778691 is a wasteful number, since it uses less digits than its factorization.

1972778691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1367190.

The product of its digits is 2667168, while the sum is 57.

The square root of 1972778691 is about 44415.9733767031. The cubic root of 1972778691 is about 1254.1788019375.

The spelling of 1972778691 in words is "one billion, nine hundred seventy-two million, seven hundred seventy-eight thousand, six hundred ninety-one".