7900400640 has 704 divisors, whose sum is σ = 30561546240. Its totient is φ = 1719336960.

The previous prime is 7900400597. The next prime is 7900400653. The reversal of 7900400640 is 460040097.

It is a tau number, because it is divible by the number of its divisors (704).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 7900400598 and 7900400607.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 73835467 + ... + 73835573.

Almost surely, 2^7900400640 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 7900400640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (15280773120).

7900400640 is an abundant number, since it is smaller than the sum of its proper divisors (22661145600).

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

7900400640 is a wasteful number, since it uses less digits than its factorization.

7900400640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 188 (or 170 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 30.

The square root of 7900400640 is about 88884.1979206653. The cubic root of 7900400640 is about 1991.6653685404.

The spelling of 7900400640 in words is "seven billion, nine hundred million, four hundred thousand, six hundred forty".