661707819 has 32 divisors (see below), whose sum is σ = 1016409600. Its totient is φ = 424962720.

The previous prime is 661707817. The next prime is 661707857. The reversal of 661707819 is 918707166.

661707819 = T₃₆₇ + T₃₆₈ + ... + T₁₅₈₉.

It is not a de Polignac number, because 661707819 - 2¹ = 661707817 is a prime.

It is a super-2 number, since 2×661707819² = 875714475451473522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (661707811) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 540442 + ... + 541664.

It is an arithmetic number, because the mean of its divisors is an integer number (31762800).

Almost surely, 2^661707819 is an apocalyptic number.

661707819 is a deficient number, since it is larger than the sum of its proper divisors (354701781).

661707819 is a wasteful number, since it uses less digits than its factorization.

661707819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1952 (or 1946 counting only the distinct ones).

The product of its (nonzero) digits is 127008, while the sum is 45.

The square root of 661707819 is about 25723.6820653654. The cubic root of 661707819 is about 871.4090958356.

The spelling of 661707819 in words is "six hundred sixty-one million, seven hundred seven thousand, eight hundred nineteen".