1651516991 has 4 divisors (see below), whose sum is σ = 1655331552. Its totient is φ = 1647702432.

The previous prime is 1651516961. The next prime is 1651517009. The reversal of 1651516991 is 1996151561.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1651516991 - 2¹⁴ = 1651500607 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 (1651516921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1906631 + ... + 1907496.

It is an arithmetic number, because the mean of its divisors is an integer number (413832888).

Almost surely, 2^1651516991 is an apocalyptic number.

1651516991 is a deficient number, since it is larger than the sum of its proper divisors (3814561).

1651516991 is an equidigital number, since it uses as much as digits as its factorization.

1651516991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3814560.

The product of its digits is 72900, while the sum is 44.

The square root of 1651516991 is about 40638.8606016458. The cubic root of 1651516991 is about 1182.0277761707.

The spelling of 1651516991 in words is "one billion, six hundred fifty-one million, five hundred sixteen thousand, nine hundred ninety-one".