1638357749 has 16 divisors (see below), whose sum is σ = 1918844928. Its totient is φ = 1369578672.

The previous prime is 1638357727. The next prime is 1638357769. The reversal of 1638357749 is 9477538361.

It is a de Polignac number, because none of the positive numbers 2^k-1638357749 is a prime.

It is a super-2 number, since 2×1638357749² = 5368432227416694002, which contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1638357749.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1638357769) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 215084 + ... + 222570.

It is an arithmetic number, because the mean of its divisors is an integer number (119927808).

Almost surely, 2^1638357749 is an apocalyptic number.

It is an amenable number.

1638357749 is a deficient number, since it is larger than the sum of its proper divisors (280487179).

1638357749 is an equidigital number, since it uses as much as digits as its factorization.

1638357749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8264.

The product of its digits is 3810240, while the sum is 53.

The square root of 1638357749 is about 40476.6321350974. The cubic root of 1638357749 is about 1178.8799457529.

The spelling of 1638357749 in words is "one billion, six hundred thirty-eight million, three hundred fifty-seven thousand, seven hundred forty-nine".