661378049769 has 16 divisors (see below), whose sum is σ = 913192062464. Its totient is φ = 425332252800.

The previous prime is 661378049767. The next prime is 661378049819. The reversal of 661378049769 is 967940873166.

It is not a de Polignac number, because 661378049769 - 2¹ = 661378049767 is a prime.

It is a super-2 number, since 2×661378049769² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661378049767) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11331262 + ... + 11389479.

It is an arithmetic number, because the mean of its divisors is an integer number (57074503904).

Almost surely, 2^661378049769 is an apocalyptic number.

It is an amenable number.

661378049769 is a deficient number, since it is larger than the sum of its proper divisors (251814012695).

661378049769 is a wasteful number, since it uses less digits than its factorization.

661378049769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22721088.

The product of its (nonzero) digits is 82301184, while the sum is 66.

The spelling of 661378049769 in words is "six hundred sixty-one billion, three hundred seventy-eight million, forty-nine thousand, seven hundred sixty-nine".