661070772 has 72 divisors (see below), whose sum is σ = 1793695176. Its totient is φ = 204539904.

The previous prime is 661070731. The next prime is 661070779. The reversal of 661070772 is 277070166.

It can be written as a sum of positive squares in 4 ways, for example, as 155900196 + 505170576 = 12486^2 + 22476^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661070779) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 37278 + ... + 52074.

It is an arithmetic number, because the mean of its divisors is an integer number (24912433).

Almost surely, 2^661070772 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 661070772, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (896847588).

661070772 is an abundant number, since it is smaller than the sum of its proper divisors (1132624404).

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

661070772 is a wasteful number, since it uses less digits than its factorization.

661070772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14897 (or 14892 counting only the distinct ones).

The product of its (nonzero) digits is 24696, while the sum is 36.

The square root of 661070772 is about 25711.2965834086. The cubic root of 661070772 is about 871.1293617010.

The spelling of 661070772 in words is "six hundred sixty-one million, seventy thousand, seven hundred seventy-two".