646021249 has 4 divisors (see below), whose sum is σ = 647938564. Its totient is φ = 644103936.

The previous prime is 646021241. The next prime is 646021279. The reversal of 646021249 is 942120646.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 942120646 = 2 ⋅471060323.

It can be written as a sum of positive squares in 2 ways, for example, as 474934849 + 171086400 = 21793^2 + 13080^2 .

It is a cyclic number.

It is not a de Polignac number, because 646021249 - 2³ = 646021241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646021241) 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, 958152 + ... + 958825.

It is an arithmetic number, because the mean of its divisors is an integer number (161984641).

Almost surely, 2^646021249 is an apocalyptic number.

It is an amenable number.

646021249 is a deficient number, since it is larger than the sum of its proper divisors (1917315).

646021249 is a wasteful number, since it uses less digits than its factorization.

646021249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1917314.

The product of its (nonzero) digits is 20736, while the sum is 34.

The square root of 646021249 is about 25416.9480662018. The cubic root of 646021249 is about 864.4680253370.

The spelling of 646021249 in words is "six hundred forty-six million, twenty-one thousand, two hundred forty-nine".