66390249 has 4 divisors (see below), whose sum is σ = 88520336. Its totient is φ = 44260164.

The previous prime is 66390239. The next prime is 66390271. The reversal of 66390249 is 94209366.

66390249 = 1912² + 1913² + ... + 1929².

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 66390249 - 2¹² = 66386153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66390239) 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, 11065039 + ... + 11065044.

It is an arithmetic number, because the mean of its divisors is an integer number (22130084).

Almost surely, 2^66390249 is an apocalyptic number.

It is an amenable number.

66390249 is a deficient number, since it is larger than the sum of its proper divisors (22130087).

66390249 is a wasteful number, since it uses less digits than its factorization.

66390249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22130086.

The product of its (nonzero) digits is 69984, while the sum is 39.

The square root of 66390249 is about 8148.0211708120. The cubic root of 66390249 is about 404.9189473526.

The spelling of 66390249 in words is "sixty-six million, three hundred ninety thousand, two hundred forty-nine".