661456890 has 36 divisors (see below), whose sum is σ = 1720422522. Its totient is φ = 176323440.

The previous prime is 661456883. The next prime is 661456891. The reversal of 661456890 is 98654166.

It can be written as a sum of positive squares in only one way, i.e., 595311201 + 66145689 = 24399^2 + 8133^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (661456891) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 242635 + ... + 245345.

Almost surely, 2^661456890 is an apocalyptic number.

661456890 is an abundant number, since it is smaller than the sum of its proper divisors (1058965632).

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

661456890 is an equidigital number, since it uses as much as digits as its factorization.

661456890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5435 (or 2721 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 45.

The square root of 661456890 is about 25718.8042101494. The cubic root of 661456890 is about 871.2989316753.

It can be divided in two parts, 6614 and 56890, that added together give a square (63504 = 252²).

The spelling of 661456890 in words is "six hundred sixty-one million, four hundred fifty-six thousand, eight hundred ninety".