1630640781 has 64 divisors (see below), whose sum is σ = 3170457600. Its totient is φ = 802483200.

The previous prime is 1630640777. The next prime is 1630640789. The reversal of 1630640781 is 1870460361.

1630640781 is a `hidden beast` number, since 1 + 6 + 3 + 0 + 640 + 7 + 8 + 1 = 666.

It is not a de Polignac number, because 1630640781 - 2² = 1630640777 is a prime.

It is a super-2 number, since 2×1630640781² = 5317978713320579922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1630640789) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 18861 + ... + 60141.

It is an arithmetic number, because the mean of its divisors is an integer number (49538400).

Almost surely, 2^1630640781 is an apocalyptic number.

1630640781 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1630640781 is a deficient number, since it is larger than the sum of its proper divisors (1539816819).

1630640781 is a wasteful number, since it uses less digits than its factorization.

1630640781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41327 (or 41321 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 1630640781 is about 40381.1934073276. The cubic root of 1630640781 is about 1177.0261178852.

It can be divided in two parts, 1630 and 640781, that added together give a triangular number (642411 = T₁₁₃₃).

The spelling of 1630640781 in words is "one billion, six hundred thirty million, six hundred forty thousand, seven hundred eighty-one".