638453890 has 16 divisors (see below), whose sum is σ = 1149525432. Its totient is φ = 255313024.

The previous prime is 638453869. The next prime is 638453899. The reversal of 638453890 is 98354836.

It can be written as a sum of positive squares in 4 ways, for example, as 637613001 + 840889 = 25251^2 + 917^2 .

It is a super-2 number, since 2×638453890² = 815246739312264200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 638453890.

It is not an unprimeable number, because it can be changed into a prime (638453899) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48942 + ... + 60598.

Almost surely, 2^638453890 is an apocalyptic number.

638453890 is a deficient number, since it is larger than the sum of its proper divisors (511071542).

638453890 is a wasteful number, since it uses less digits than its factorization.

638453890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17141.

The product of its (nonzero) digits is 622080, while the sum is 46.

The square root of 638453890 is about 25267.6451217758. The cubic root of 638453890 is about 861.0793595631.

The spelling of 638453890 in words is "six hundred thirty-eight million, four hundred fifty-three thousand, eight hundred ninety".