15515045621 has 2 divisors, whose sum is σ = 15515045622. Its totient is φ = 15515045620.

The previous prime is 15515045569. The next prime is 15515045659. The reversal of 15515045621 is 12654051551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8260264996 + 7254780625 = 90886^2 + 85175^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15515045621 is a prime.

It is a super-2 number, since 2×15515045621² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15515045521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7757522810 + 7757522811.

It is an arithmetic number, because the mean of its divisors is an integer number (7757522811).

Almost surely, 2^15515045621 is an apocalyptic number.

It is an amenable number.

15515045621 is a deficient number, since it is larger than the sum of its proper divisors (1).

15515045621 is an equidigital number, since it uses as much as digits as its factorization.

15515045621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 30000, while the sum is 35.

The spelling of 15515045621 in words is "fifteen billion, five hundred fifteen million, forty-five thousand, six hundred twenty-one".