661948878 has 32 divisors (see below), whose sum is σ = 1402096896. Its totient is φ = 207903168.

The previous prime is 661948871. The next prime is 661948919. The reversal of 661948878 is 878849166.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661948871) 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, 26551 + ... + 45042.

It is an arithmetic number, because the mean of its divisors is an integer number (43815528).

Almost surely, 2^661948878 is an apocalyptic number.

661948878 is an abundant number, since it is smaller than the sum of its proper divisors (740148018).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661948878 is a wasteful number, since it uses less digits than its factorization.

661948878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71688.

The product of its digits is 4644864, while the sum is 57.

The square root of 661948878 is about 25728.3671848798. The cubic root of 661948878 is about 871.5149005911.

The spelling of 661948878 in words is "six hundred sixty-one million, nine hundred forty-eight thousand, eight hundred seventy-eight".