21002120205 has 32 divisors (see below), whose sum is σ = 36777742848. Its totient is φ = 10149652800.

The previous prime is 21002120197. The next prime is 21002120213. The reversal of 21002120205 is 50202120012.

It is an interprime number because it is at equal distance from previous prime (21002120197) and next prime (21002120213).

It is not a de Polignac number, because 21002120205 - 2³ = 21002120197 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 156651 + ... + 257960.

It is an arithmetic number, because the mean of its divisors is an integer number (1149304464).

Almost surely, 2^21002120205 is an apocalyptic number.

It is an amenable number.

21002120205 is a deficient number, since it is larger than the sum of its proper divisors (15775622643).

21002120205 is a wasteful number, since it uses less digits than its factorization.

21002120205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 414937.

The product of its (nonzero) digits is 80, while the sum is 15.

Adding to 21002120205 its reverse (50202120012), we get a palindrome (71204240217).

The spelling of 21002120205 in words is "twenty-one billion, two million, one hundred twenty thousand, two hundred five".