661652220 has 96 divisors (see below), whose sum is σ = 1928134656. Its totient is φ = 169344000.

The previous prime is 661652171. The next prime is 661652221. The reversal of 661652220 is 22256166.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661652221) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 234820 + ... + 237620.

It is an arithmetic number, because the mean of its divisors is an integer number (20084736).

Almost surely, 2^661652220 is an apocalyptic number.

661652220 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661652220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (964067328).

661652220 is an abundant number, since it is smaller than the sum of its proper divisors (1266482436).

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

661652220 is a wasteful number, since it uses less digits than its factorization.

661652220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2971 (or 2969 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 661652220 is about 25722.6013458981. The cubic root of 661652220 is about 871.3846888743.

The spelling of 661652220 in words is "six hundred sixty-one million, six hundred fifty-two thousand, two hundred twenty".