661227840 has 672 divisors, whose sum is σ = 2973384960. Its totient is φ = 134701056.

The previous prime is 661227839. The next prime is 661227857. The reversal of 661227840 is 48722166.

It is a tau number, because it is divible by the number of its divisors (672).

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

It is a junction number, because it is equal to n+sod(n) for n = 661227795 and 661227804.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 22800946 + ... + 22800974.

It is an arithmetic number, because the mean of its divisors is an integer number (4424680).

Almost surely, 2^661227840 is an apocalyptic number.

661227840 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 661227840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1486692480).

661227840 is an abundant number, since it is smaller than the sum of its proper divisors (2312157120).

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

661227840 is a wasteful number, since it uses less digits than its factorization.

661227840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104 (or 59 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 36.

The square root of 661227840 is about 25714.3508570603. The cubic root of 661227840 is about 871.1983486221.

The spelling of 661227840 in words is "six hundred sixty-one million, two hundred twenty-seven thousand, eight hundred forty".