661620276 has 36 divisors (see below), whose sum is σ = 1679628132. Its totient is φ = 219590784.

The previous prime is 661620247. The next prime is 661620287. The reversal of 661620276 is 672026166.

661620276 is a `hidden beast` number, since 6 + 6 + 1 + 620 + 27 + 6 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 183060900 + 478559376 = 13530^2 + 21876^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×661620276² = 875482779228632352, which contains 22 as substring.

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

It is a self number, because there is not a number n which added to its sum of digits gives 661620276.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 31051 + ... + 47826.

It is an arithmetic number, because the mean of its divisors is an integer number (46656337).

Almost surely, 2^661620276 is an apocalyptic number.

It is an amenable number.

661620276 is an abundant number, since it is smaller than the sum of its proper divisors (1018007856).

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

661620276 is a wasteful number, since it uses less digits than its factorization.

661620276 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79120 (or 79115 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 36.

The square root of 661620276 is about 25721.9804058708. The cubic root of 661620276 is about 871.3706654142.

The spelling of 661620276 in words is "six hundred sixty-one million, six hundred twenty thousand, two hundred seventy-six".