1634403991 has 12 divisors (see below), whose sum is σ = 1834723296. Its totient is φ = 1454203520.

The previous prime is 1634403977. The next prime is 1634404003. The reversal of 1634403991 is 1993044361.

It is not a de Polignac number, because 1634403991 - 2¹¹ = 1634401943 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1634403931) 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, 138010 + ... + 149383.

It is an arithmetic number, because the mean of its divisors is an integer number (152893608).

Almost surely, 2^1634403991 is an apocalyptic number.

1634403991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1634403991 is a deficient number, since it is larger than the sum of its proper divisors (200319305).

1634403991 is a wasteful number, since it uses less digits than its factorization.

1634403991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 287462 (or 287451 counting only the distinct ones).

The product of its (nonzero) digits is 69984, while the sum is 40.

The square root of 1634403991 is about 40427.7626266901. The cubic root of 1634403991 is about 1177.9308733384.

The spelling of 1634403991 in words is "one billion, six hundred thirty-four million, four hundred three thousand, nine hundred ninety-one".