661899072 has 56 divisors (see below), whose sum is σ = 1757875072. Its totient is φ = 219801600.

The previous prime is 661899071. The next prime is 661899079. The reversal of 661899072 is 270998166.

661899072 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×661899072² = 876220763028922368, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661899071) 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, 45672 + ... + 58392.

Almost surely, 2^661899072 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661899072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (878937536).

661899072 is an abundant number, since it is smaller than the sum of its proper divisors (1095976000).

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

661899072 is a wasteful number, since it uses less digits than its factorization.

661899072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13007 (or 12997 counting only the distinct ones).

The product of its (nonzero) digits is 326592, while the sum is 48.

The square root of 661899072 is about 25727.3992467175. The cubic root of 661899072 is about 871.4930420251.

The spelling of 661899072 in words is "six hundred sixty-one million, eight hundred ninety-nine thousand, seventy-two".