642521707 has 2 divisors, whose sum is σ = 642521708. Its totient is φ = 642521706.

The previous prime is 642521699. The next prime is 642521791. The reversal of 642521707 is 707125246.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 642521707 - 2³ = 642521699 is a prime.

It is not a weakly prime, because it can be changed into another prime (642521207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321260853 + 321260854.

It is an arithmetic number, because the mean of its divisors is an integer number (321260854).

Almost surely, 2^642521707 is an apocalyptic number.

642521707 is a deficient number, since it is larger than the sum of its proper divisors (1).

642521707 is an equidigital number, since it uses as much as digits as its factorization.

642521707 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23520, while the sum is 34.

The square root of 642521707 is about 25348.0118944268. The cubic root of 642521707 is about 862.9042370893.

The spelling of 642521707 in words is "six hundred forty-two million, five hundred twenty-one thousand, seven hundred seven".