21000002001 has 8 divisors (see below), whose sum is σ = 30545457504. Its totient is φ = 12727273920.

The previous prime is 21000001987. The next prime is 21000002003. The reversal of 21000002001 is 10020000012.

It is a happy number.

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

It is not a de Polignac number, because 21000002001 - 2²⁷ = 20865784273 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21000002003) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 318181816 + ... + 318181881.

It is an arithmetic number, because the mean of its divisors is an integer number (3818182188).

Almost surely, 2^21000002001 is an apocalyptic number.

It is an amenable number.

21000002001 is a deficient number, since it is larger than the sum of its proper divisors (9545455503).

21000002001 is a wasteful number, since it uses less digits than its factorization.

21000002001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 636363711.

The product of its (nonzero) digits is 4, while the sum is 6.

Adding to 21000002001 its reverse (10020000012), we get a palindrome (31020002013).

The spelling of 21000002001 in words is "twenty-one billion, two thousand, one".