531609661440 has 1664 divisors, whose sum is σ = 2274838594560. Its totient is φ = 117528330240.

The previous prime is 531609661439. The next prime is 531609661507. The reversal of 531609661440 is 44166906135.

531609661440 is a `hidden beast` number, since 5 + 3 + 1 + 60 + 96 + 61 + 440 = 666.

It is a tau number, because it is divible by the number of its divisors (1664).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 6404935639 + ... + 6404935721.

Almost surely, 2^531609661440 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 531609661440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1137419297280).

531609661440 is an abundant number, since it is smaller than the sum of its proper divisors (1743228933120).

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

531609661440 is an equidigital number, since it uses as much as digits as its factorization.

531609661440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157 (or 117 counting only the distinct ones).

The product of its (nonzero) digits is 466560, while the sum is 45.

The spelling of 531609661440 in words is "five hundred thirty-one billion, six hundred nine million, six hundred sixty-one thousand, four hundred forty".