661899942 has 48 divisors (see below), whose sum is σ = 1582111440. Its totient is φ = 198316800.

The previous prime is 661899907. The next prime is 661899949. The reversal of 661899942 is 249998166.

It is a super-2 number, since 2×661899942² = 876223066439206728, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661899949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1159 + ... + 36402.

It is an arithmetic number, because the mean of its divisors is an integer number (32960655).

Almost surely, 2^661899942 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661899942, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (791055720).

661899942 is an abundant number, since it is smaller than the sum of its proper divisors (920211498).

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

661899942 is a wasteful number, since it uses less digits than its factorization.

661899942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37669 (or 37666 counting only the distinct ones).

The product of its digits is 1679616, while the sum is 54.

The square root of 661899942 is about 25727.4161547560. The cubic root of 661899942 is about 871.4934238550.

The spelling of 661899942 in words is "six hundred sixty-one million, eight hundred ninety-nine thousand, nine hundred forty-two".