15500001001 has 9 divisors (see below), whose sum is σ = 16206208599. Its totient is φ = 14823348936.

The previous prime is 15500000993. The next prime is 15500001067. The reversal of 15500001001 is 10010000551.

The square root of 15500001001 is 124499.

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., 3372705625 + 12127295376 = 58075^2 + 110124^2 .

It is not a de Polignac number, because 15500001001 - 2³ = 15500000993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15500001091) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2860771 + ... + 2866183.

Almost surely, 2^15500001001 is an apocalyptic number.

15500001001 is the 124499-th square number.

15500001001 is the 62250-th centered octagonal number.

It is an amenable number.

15500001001 is a deficient number, since it is larger than the sum of its proper divisors (706207598).

15500001001 is an frugal number, since it uses more digits than its factorization.

15500001001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10872 (or 5436 counting only the distinct ones).

The product of its (nonzero) digits is 25, while the sum is 13.

Multiplying 15500001001 by its product of nonzero digits (25), we get a square (387500025025 = 622495²).

Adding to 15500001001 its reverse (10010000551), we get a palindrome (25510001552).

The spelling of 15500001001 in words is "fifteen billion, five hundred million, one thousand, one".