15515220402 has 72 divisors (see below), whose sum is σ = 37084995948. Its totient is φ = 4684426560.

The previous prime is 15515220389. The next prime is 15515220419. The reversal of 15515220402 is 20402251551.

15515220402 is a `hidden beast` number, since 1 + 551 + 52 + 20 + 40 + 2 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 15256943361 + 258277041 = 123519^2 + 16071^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 590448 + ... + 616164.

Almost surely, 2^15515220402 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 15515220402, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (18542497974).

15515220402 is an abundant number, since it is smaller than the sum of its proper divisors (21569775546).

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

15515220402 is a wasteful number, since it uses less digits than its factorization.

15515220402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26024 (or 26010 counting only the distinct ones).

The product of its (nonzero) digits is 4000, while the sum is 27.

Adding to 15515220402 its reverse (20402251551), we get a palindrome (35917471953).

The spelling of 15515220402 in words is "fifteen billion, five hundred fifteen million, two hundred twenty thousand, four hundred two".