661425408 has 108 divisors (see below), whose sum is σ = 2179541728. Its totient is φ = 188974080.

The previous prime is 661425403. The next prime is 661425463. The reversal of 661425408 is 804524166.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

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 (661425403) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4378 + ... + 36633.

Almost surely, 2^661425408 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 661425408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1089770864).

661425408 is an abundant number, since it is smaller than the sum of its proper divisors (1518116320).

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

661425408 is a wasteful number, since it uses less digits than its factorization.

661425408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41040 (or 41023 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 36.

The square root of 661425408 is about 25718.1921604144. The cubic root of 661425408 is about 871.2851083163.

The spelling of 661425408 in words is "six hundred sixty-one million, four hundred twenty-five thousand, four hundred eight".