642470409 has 81 divisors (see below), whose sum is σ = 1163141031. Its totient is φ = 340663680.

The previous prime is 642470383. The next prime is 642470419. The reversal of 642470409 is 904074246.

642470409 = T₂₄₇ + T₂₄₈ + ... + T₁₅₆₉.

The square root of 642470409 is 25347.

It is a perfect power (a square), and thus also a powerful number.

642470409 is a `hidden beast` number, since 6 + 4 + 247 + 0 + 409 = 666.

It can be written as a sum of positive squares in only one way, i.e., 500193225 + 142277184 = 22365^2 + 11928^2 .

It is not a de Polignac number, because 642470409 - 2⁷ = 642470281 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (642470419) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 9048844 + ... + 9048914.

Almost surely, 2^642470409 is an apocalyptic number.

642470409 is the 25347-th square number.

642470409 is the 12674-th centered octagonal number.

It is an amenable number.

642470409 is a deficient number, since it is larger than the sum of its proper divisors (520670622).

642470409 is a wasteful number, since it uses less digits than its factorization.

642470409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 196 (or 98 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 36.

The cubic root of 642470409 is about 862.8812721378.

Multiplying 642470409 by its sum of digits (36), we get a square (23128934724 = 152082²).

The spelling of 642470409 in words is "six hundred forty-two million, four hundred seventy thousand, four hundred nine".