634380921 has 18 divisors (see below), whose sum is σ = 932168250. Its totient is φ = 415731936.

The previous prime is 634380913. The next prime is 634380973. The reversal of 634380921 is 129083436.

It can be written as a sum of positive squares in only one way, i.e., 489515625 + 144865296 = 22125^2 + 12036^2 .

It is not a de Polignac number, because 634380921 - 2³ = 634380913 is a prime.

It is a super-5 number, since 5×634380921⁵ (a number of 45 digits) contains 55555 as substring.

It is not an unprimeable number, because it can be changed into a prime (634380121) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 21205 + ... + 41453.

It is an arithmetic number, because the mean of its divisors is an integer number (51787125).

Almost surely, 2^634380921 is an apocalyptic number.

It is an amenable number.

634380921 is a deficient number, since it is larger than the sum of its proper divisors (297787329).

634380921 is a wasteful number, since it uses less digits than its factorization.

634380921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20373 (or 20311 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 634380921 is about 25186.9196409565. The cubic root of 634380921 is about 859.2443881297.

The spelling of 634380921 in words is "six hundred thirty-four million, three hundred eighty thousand, nine hundred twenty-one".