661499994 has 16 divisors (see below), whose sum is σ = 1323252000. Its totient is φ = 220458000.

The previous prime is 661499989. The next prime is 661499999. The reversal of 661499994 is 499994166.

It is an interprime number because it is at equal distance from previous prime (661499989) and next prime (661499999).

It is not an unprimeable number, because it can be changed into a prime (661499999) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 57744 + ... + 68244.

It is an arithmetic number, because the mean of its divisors is an integer number (82703250).

Almost surely, 2^661499994 is an apocalyptic number.

661499994 is an abundant number, since it is smaller than the sum of its proper divisors (661752006).

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

661499994 is a wasteful number, since it uses less digits than its factorization.

661499994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21005.

The product of its digits is 3779136, while the sum is 57.

The square root of 661499994 is about 25719.6421825810. The cubic root of 661499994 is about 871.3178574002.

The spelling of 661499994 in words is "six hundred sixty-one million, four hundred ninety-nine thousand, nine hundred ninety-four".