21221001021 has 16 divisors (see below), whose sum is σ = 31172528448. Its totient is φ = 12733872000.

The previous prime is 21221001019. The next prime is 21221001023. The reversal of 21221001021 is 12010012212.

It is an interprime number because it is at equal distance from previous prime (21221001019) and next prime (21221001023).

It is not a de Polignac number, because 21221001021 - 2¹ = 21221001019 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21221000988 and 21221001006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221001023) 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, 3180136 + ... + 3186801.

It is an arithmetic number, because the mean of its divisors is an integer number (1948283028).

Almost surely, 2^21221001021 is an apocalyptic number.

It is an amenable number.

21221001021 is a deficient number, since it is larger than the sum of its proper divisors (9951527427).

21221001021 is a wasteful number, since it uses less digits than its factorization.

21221001021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6367052.

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21221001021 its reverse (12010012212), we get a palindrome (33231013233).

The spelling of 21221001021 in words is "twenty-one billion, two hundred twenty-one million, one thousand, twenty-one".