21000021401 has 8 divisors (see below), whose sum is σ = 21772557000. Its totient is φ = 20230712320.

The previous prime is 21000021389. The next prime is 21000021403. The reversal of 21000021401 is 10412000012.

It can be written as a sum of positive squares in 4 ways, for example, as 2031845776 + 18968175625 = 45076^2 + 137725^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21000021401 - 2¹⁴ = 21000005017 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21000021403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 793370 + ... + 819411.

It is an arithmetic number, because the mean of its divisors is an integer number (2721569625).

Almost surely, 2^21000021401 is an apocalyptic number.

It is an amenable number.

21000021401 is a deficient number, since it is larger than the sum of its proper divisors (772535599).

21000021401 is a wasteful number, since it uses less digits than its factorization.

21000021401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1613259.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21000021401 its reverse (10412000012), we get a palindrome (31412021413).

The spelling of 21000021401 in words is "twenty-one billion, twenty-one thousand, four hundred one".