645134521 has 16 divisors (see below), whose sum is σ = 700305408. Its totient is φ = 592534800.

The previous prime is 645134453. The next prime is 645134533. The reversal of 645134521 is 125431546.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 645134521 - 2⁷ = 645134393 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645134591) 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, 89950 + ... + 96856.

It is an arithmetic number, because the mean of its divisors is an integer number (43769088).

Almost surely, 2^645134521 is an apocalyptic number.

It is an amenable number.

645134521 is a deficient number, since it is larger than the sum of its proper divisors (55170887).

645134521 is a wasteful number, since it uses less digits than its factorization.

645134521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7092.

The product of its digits is 14400, while the sum is 31.

The square root of 645134521 is about 25399.4984399299. The cubic root of 645134521 is about 864.0723216389.

The spelling of 645134521 in words is "six hundred forty-five million, one hundred thirty-four thousand, five hundred twenty-one".