19811402 has 8 divisors (see below), whose sum is σ = 32003076. Its totient is φ = 9143712.

The previous prime is 19811399. The next prime is 19811411. The reversal of 19811402 is 20411891.

It is a Cunningham number, because it is equal to 4451²+1.

It can be written as a sum of positive squares in 2 ways, for example, as 19811401 + 1 = 4451^2 + 1^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Harshad number since it is a multiple of its sum of digits (26), and also a Moran number because the ratio is a prime number: 761977 = 19811402 / (1 + 9 + 8 + 1 + 1 + 4 + 0 + 2).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 380963 + ... + 381014.

Almost surely, 2^19811402 is an apocalyptic number.

19811402 is a deficient number, since it is larger than the sum of its proper divisors (12191674).

19811402 is a wasteful number, since it uses less digits than its factorization.

19811402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 761992.

The product of its (nonzero) digits is 576, while the sum is 26.

The square root of 19811402 is about 4451.0001123343. Note that the first 3 decimals coincide. The cubic root of 19811402 is about 270.5858426954.

The spelling of 19811402 in words is "nineteen million, eight hundred eleven thousand, four hundred two".