3972781 has 4 divisors (see below), whose sum is σ = 4206492. Its totient is φ = 3739072.

The previous prime is 3972757. The next prime is 3972791. The reversal of 3972781 is 1872793.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1872793 = 13 ⋅144061.

It can be written as a sum of positive squares in 2 ways, for example, as 3575881 + 396900 = 1891^2 + 630^2 .

It is a cyclic number.

It is not a de Polignac number, because 3972781 - 2¹³ = 3964589 is a prime.

It is a super-2 number, since 2×3972781² = 31565977747922, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 3972781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3972751) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 116830 + ... + 116863.

It is an arithmetic number, because the mean of its divisors is an integer number (1051623).

Almost surely, 2^3972781 is an apocalyptic number.

It is an amenable number.

3972781 is a deficient number, since it is larger than the sum of its proper divisors (233711).

3972781 is a wasteful number, since it uses less digits than its factorization.

3972781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 233710.

The product of its digits is 21168, while the sum is 37.

The square root of 3972781 is about 1993.1836342896. The cubic root of 3972781 is about 158.3792231404.

It can be divided in two parts, 3972 and 781, that added together give a triangular number (4753 = T₉₇).

The spelling of 3972781 in words is "three million, nine hundred seventy-two thousand, seven hundred eighty-one".