66445551 has 24 divisors (see below), whose sum is σ = 100620000. Its totient is φ = 42172416.

The previous prime is 66445529. The next prime is 66445553. The reversal of 66445551 is 15554466.

66445551 is a `hidden beast` number, since 6 + 64 + 45 + 551 = 666.

It is not a de Polignac number, because 66445551 - 2⁶ = 66445487 is a prime.

It is a super-2 number, since 2×66445551² = 8830022495387202, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66445553) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 52575 + ... + 53823.

It is an arithmetic number, because the mean of its divisors is an integer number (4192500).

Almost surely, 2^66445551 is an apocalyptic number.

66445551 is a deficient number, since it is larger than the sum of its proper divisors (34174449).

66445551 is a wasteful number, since it uses less digits than its factorization.

66445551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1535 (or 1532 counting only the distinct ones).

The product of its digits is 72000, while the sum is 36.

The square root of 66445551 is about 8151.4140491083. The cubic root of 66445551 is about 405.0313464535.

The spelling of 66445551 in words is "sixty-six million, four hundred forty-five thousand, five hundred fifty-one".