1611878381 has 2 divisors, whose sum is σ = 1611878382. Its totient is φ = 1611878380.

The previous prime is 1611878371. The next prime is 1611878413. The reversal of 1611878381 is 1838781161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1596402025 + 15476356 = 39955^2 + 3934^2 .

It is a cyclic number.

It is not a de Polignac number, because 1611878381 - 2¹⁴ = 1611861997 is a prime.

It is a super-2 number, since 2×1611878381² = 5196303830270362322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1611878321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 805939190 + 805939191.

It is an arithmetic number, because the mean of its divisors is an integer number (805939191).

Almost surely, 2^1611878381 is an apocalyptic number.

It is an amenable number.

1611878381 is a deficient number, since it is larger than the sum of its proper divisors (1).

1611878381 is an equidigital number, since it uses as much as digits as its factorization.

1611878381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64512, while the sum is 44.

The square root of 1611878381 is about 40148.2052027236. The cubic root of 1611878381 is about 1172.4943451218.

The spelling of 1611878381 in words is "one billion, six hundred eleven million, eight hundred seventy-eight thousand, three hundred eighty-one".