1651616521 has 8 divisors (see below), whose sum is σ = 1768421160. Its totient is φ = 1536995328.

The previous prime is 1651616513. The next prime is 1651616557. The reversal of 1651616521 is 1256161561.

It can be written as a sum of positive squares in 4 ways, for example, as 731161600 + 920454921 = 27040^2 + 30339^2 .

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 1651616521 - 2³ = 1651616513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1651616501) 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, 544296 + ... + 547321.

It is an arithmetic number, because the mean of its divisors is an integer number (221052645).

Almost surely, 2^1651616521 is an apocalyptic number.

It is an amenable number.

1651616521 is a deficient number, since it is larger than the sum of its proper divisors (116804639).

1651616521 is a wasteful number, since it uses less digits than its factorization.

1651616521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1091723.

The product of its digits is 10800, while the sum is 34.

The square root of 1651616521 is about 40640.0851500092. The cubic root of 1651616521 is about 1182.0515209786.

The spelling of 1651616521 in words is "one billion, six hundred fifty-one million, six hundred sixteen thousand, five hundred twenty-one".