1638742220 has 12 divisors (see below), whose sum is σ = 3441358704. Its totient is φ = 655496880.

The previous prime is 1638742211. The next prime is 1638742223. The reversal of 1638742220 is 222478361.

It is a super-2 number, since 2×1638742220² = 5370952127221056800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1638742223) 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, 40968536 + ... + 40968575.

It is an arithmetic number, because the mean of its divisors is an integer number (286779892).

Almost surely, 2^1638742220 is an apocalyptic number.

1638742220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1638742220 is an abundant number, since it is smaller than the sum of its proper divisors (1802616484).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1638742220 is a wasteful number, since it uses less digits than its factorization.

1638742220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81937120 (or 81937118 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 35.

The square root of 1638742220 is about 40481.3811523273. The cubic root of 1638742220 is about 1178.9721538807.

The spelling of 1638742220 in words is "one billion, six hundred thirty-eight million, seven hundred forty-two thousand, two hundred twenty".