55781806 has 4 divisors (see below), whose sum is σ = 83672712. Its totient is φ = 27890902.

The previous prime is 55781783. The next prime is 55781833. The reversal of 55781806 is 60818755.

It is a semiprime because it is the product of two primes.

It is a super-2 number, since 2×55781806² = 6223219761243272, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13945450 + ... + 13945453.

It is an arithmetic number, because the mean of its divisors is an integer number (20918178).

Almost surely, 2^55781806 is an apocalyptic number.

55781806 is a deficient number, since it is larger than the sum of its proper divisors (27890906).

55781806 is a wasteful number, since it uses less digits than its factorization.

55781806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27890905.

The product of its (nonzero) digits is 67200, while the sum is 40.

The square root of 55781806 is about 7468.7218451352. The cubic root of 55781806 is about 382.0886968184.

The spelling of 55781806 in words is "fifty-five million, seven hundred eighty-one thousand, eight hundred six".