20551615221 has 16 divisors (see below), whose sum is σ = 28874278400. Its totient is φ = 12966509808.

The previous prime is 20551615171. The next prime is 20551615237. The reversal of 20551615221 is 12251615502.

It is not a de Polignac number, because 20551615221 - 2¹⁰ = 20551614197 is a prime.

It is a super-3 number, since 3×20551615221³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20551615421) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 131311 + ... + 241548.

It is an arithmetic number, because the mean of its divisors is an integer number (1804642400).

Almost surely, 2^20551615221 is an apocalyptic number.

It is an amenable number.

20551615221 is a deficient number, since it is larger than the sum of its proper divisors (8322663179).

20551615221 is a wasteful number, since it uses less digits than its factorization.

20551615221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 373848.

The product of its (nonzero) digits is 6000, while the sum is 30.

The spelling of 20551615221 in words is "twenty billion, five hundred fifty-one million, six hundred fifteen thousand, two hundred twenty-one".