1651661645 has 8 divisors (see below), whose sum is σ = 1983148056. Its totient is φ = 1320559936.

The previous prime is 1651661633. The next prime is 1651661647. The reversal of 1651661645 is 5461661561.

It can be written as a sum of positive squares in 4 ways, for example, as 159693769 + 1491967876 = 12637^2 + 38626^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1651661645 - 2⁴ = 1651661629 is a prime.

It is a super-3 number, since 3×1651661645³ (a number of 29 digits) contains 333 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1651661647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 86642 + ... + 103971.

It is an arithmetic number, because the mean of its divisors is an integer number (247893507).

Almost surely, 2^1651661645 is an apocalyptic number.

It is an amenable number.

1651661645 is a deficient number, since it is larger than the sum of its proper divisors (331486411).

1651661645 is a wasteful number, since it uses less digits than its factorization.

1651661645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192351.

The product of its digits is 129600, while the sum is 41.

The square root of 1651661645 is about 40640.6403123770. The cubic root of 1651661645 is about 1182.0622858680.

The spelling of 1651661645 in words is "one billion, six hundred fifty-one million, six hundred sixty-one thousand, six hundred forty-five".