640215061 has 2 divisors, whose sum is σ = 640215062. Its totient is φ = 640215060.

The previous prime is 640215031. The next prime is 640215067. The reversal of 640215061 is 160512046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 599956036 + 40259025 = 24494^2 + 6345^2 .

It is a cyclic number.

It is not a de Polignac number, because 640215061 - 2¹³ = 640206869 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640215067) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320107530 + 320107531.

It is an arithmetic number, because the mean of its divisors is an integer number (320107531).

Almost surely, 2^640215061 is an apocalyptic number.

It is an amenable number.

640215061 is a deficient number, since it is larger than the sum of its proper divisors (1).

640215061 is an equidigital number, since it uses as much as digits as its factorization.

640215061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 640215061 is about 25302.4714405530. The cubic root of 640215061 is about 861.8703933023.

The spelling of 640215061 in words is "six hundred forty million, two hundred fifteen thousand, sixty-one".