21000022012021 has 16 divisors (see below), whose sum is σ = 22715425068336. Its totient is φ = 19298928715776.

The previous prime is 21000022011949. The next prime is 21000022012027. The reversal of 21000022012021 is 12021022000012.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 2195180044996 + 18804841967025 = 1481614^2 + 4336455^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000022012021 - 2⁷ = 21000022011893 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a junction number, because it is equal to n+sod(n) for n = 21000022011992 and 21000022012010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000022012027) 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, 23036721 + ... + 23930953.

It is an arithmetic number, because the mean of its divisors is an integer number (1419714066771).

Almost surely, 2^{21000022012021} is an apocalyptic number.

It is an amenable number.

21000022012021 is a deficient number, since it is larger than the sum of its proper divisors (1715403056315).

21000022012021 is a wasteful number, since it uses less digits than its factorization.

21000022012021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 902232.

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 21000022012021 its reverse (12021022000012), we get a palindrome (33021044012033).

The spelling of 21000022012021 in words is "twenty-one trillion, twenty-two million, twelve thousand, twenty-one".