661899907 has 2 divisors, whose sum is σ = 661899908. Its totient is φ = 661899906.

The previous prime is 661899899. The next prime is 661899949. The reversal of 661899907 is 709998166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661899907 - 2³ = 661899899 is a prime.

It is a super-2 number, since 2×661899907² = 876222973773217298, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (661899977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330949953 + 330949954.

It is an arithmetic number, because the mean of its divisors is an integer number (330949954).

Almost surely, 2^661899907 is an apocalyptic number.

661899907 is a deficient number, since it is larger than the sum of its proper divisors (1).

661899907 is an equidigital number, since it uses as much as digits as its factorization.

661899907 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1469664, while the sum is 55.

The square root of 661899907 is about 25727.4154745478. The cubic root of 661899907 is about 871.4934084940.

The spelling of 661899907 in words is "six hundred sixty-one million, eight hundred ninety-nine thousand, nine hundred seven".