21532040644 has 9 divisors (see below), whose sum is σ = 37681584717. Its totient is φ = 10765873584.

The previous prime is 21532040639. The next prime is 21532040687. The reversal of 21532040644 is 44604023512.

The square root of 21532040644 is 146738.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 28751044 + 21503289600 = 5362^2 + 146640^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 256792 + ... + 330160.

Almost surely, 2^21532040644 is an apocalyptic number.

21532040644 is the 146738-th square number.

It is an amenable number.

21532040644 is a deficient number, since it is larger than the sum of its proper divisors (16149544073).

21532040644 is an frugal number, since it uses more digits than its factorization.

21532040644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 146742 (or 73371 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 31.

The spelling of 21532040644 in words is "twenty-one billion, five hundred thirty-two million, forty thousand, six hundred forty-four".