1821651564 has 12 divisors (see below), whose sum is σ = 4250520344. Its totient is φ = 607217184.

The previous prime is 1821651539. The next prime is 1821651569. The reversal of 1821651564 is 4651561281.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (1821651569) 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, 75902137 + ... + 75902160.

Almost surely, 2^1821651564 is an apocalyptic number.

It is an amenable number.

1821651564 is an abundant number, since it is smaller than the sum of its proper divisors (2428868780).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1821651564 is a wasteful number, since it uses less digits than its factorization.

1821651564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151804304 (or 151804302 counting only the distinct ones).

The product of its digits is 57600, while the sum is 39.

The square root of 1821651564 is about 42680.8102547269. The cubic root of 1821651564 is about 1221.2983499291.

The spelling of 1821651564 in words is "one billion, eight hundred twenty-one million, six hundred fifty-one thousand, five hundred sixty-four".