661031620 has 12 divisors (see below), whose sum is σ = 1388166444. Its totient is φ = 264412640.

The previous prime is 661031617. The next prime is 661031627. The reversal of 661031620 is 26130166.

It can be written as a sum of positive squares in 2 ways, for example, as 300259584 + 360772036 = 17328^2 + 18994^2 .

It is not an unprimeable number, because it can be changed into a prime (661031627) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16525771 + ... + 16525810.

It is an arithmetic number, because the mean of its divisors is an integer number (115680537).

Almost surely, 2^661031620 is an apocalyptic number.

It is an amenable number.

661031620 is an abundant number, since it is smaller than the sum of its proper divisors (727134824).

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

661031620 is a wasteful number, since it uses less digits than its factorization.

661031620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33051590 (or 33051588 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 661031620 is about 25710.5351947407. The cubic root of 661031620 is about 871.1121637793.

Adding to 661031620 its reverse (26130166), we get a palindrome (687161786).

The spelling of 661031620 in words is "six hundred sixty-one million, thirty-one thousand, six hundred twenty".