1638249477 has 4 divisors (see below), whose sum is σ = 2184332640. Its totient is φ = 1092166316.

The previous prime is 1638249461. The next prime is 1638249493. The reversal of 1638249477 is 7749428361.

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 an interprime number because it is at equal distance from previous prime (1638249461) and next prime (1638249493).

It is a cyclic number.

It is not a de Polignac number, because 1638249477 - 2⁴ = 1638249461 is a prime.

It is a super-2 number, since 2×1638249477² = 5367722697781547058, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1638249677) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 273041577 + ... + 273041582.

It is an arithmetic number, because the mean of its divisors is an integer number (546083160).

Almost surely, 2^1638249477 is an apocalyptic number.

It is an amenable number.

1638249477 is a deficient number, since it is larger than the sum of its proper divisors (546083163).

1638249477 is an equidigital number, since it uses as much as digits as its factorization.

1638249477 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 546083162.

The product of its digits is 2032128, while the sum is 51.

The square root of 1638249477 is about 40475.2946499467. The cubic root of 1638249477 is about 1178.8539761498.

The spelling of 1638249477 in words is "one billion, six hundred thirty-eight million, two hundred forty-nine thousand, four hundred seventy-seven".