15550020621 has 6 divisors (see below), whose sum is σ = 22461140910. Its totient is φ = 10366680408.

The previous prime is 15550020611. The next prime is 15550020659. The reversal of 15550020621 is 12602005551.

15550020621 is a `hidden beast` number, since 15 + 5 + 5 + 0 + 0 + 20 + 621 = 666.

It can be written as a sum of positive squares in only one way, i.e., 13264128900 + 2285891721 = 115170^2 + 47811^2 .

It is not a de Polignac number, because 15550020621 - 2²⁹ = 15013149709 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15550020611) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 863890026 + ... + 863890043.

It is an arithmetic number, because the mean of its divisors is an integer number (3743523485).

Almost surely, 2^15550020621 is an apocalyptic number.

It is an amenable number.

15550020621 is a deficient number, since it is larger than the sum of its proper divisors (6911120289).

15550020621 is a wasteful number, since it uses less digits than its factorization.

15550020621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1727780075 (or 1727780072 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 27.

It can be divided in two parts, 155500 and 20621, that added together give a triangular number (176121 = T₅₉₃).

The spelling of 15550020621 in words is "fifteen billion, five hundred fifty million, twenty thousand, six hundred twenty-one".