21012020001 has 32 divisors (see below), whose sum is σ = 37122693120. Its totient is φ = 11484828432.

The previous prime is 21012019997. The next prime is 21012020039. The reversal of 21012020001 is 10002021012.

It is not a de Polignac number, because 21012020001 - 2² = 21012019997 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (21012021001) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2412495 + ... + 2421188.

It is an arithmetic number, because the mean of its divisors is an integer number (1160084160).

Almost surely, 2^21012020001 is an apocalyptic number.

21012020001 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21012020001 is a deficient number, since it is larger than the sum of its proper divisors (16110673119).

21012020001 is a wasteful number, since it uses less digits than its factorization.

21012020001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4833722 (or 4833716 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21012020001 its reverse (10002021012), we get a palindrome (31014041013).

The spelling of 21012020001 in words is "twenty-one billion, twelve million, twenty thousand, one".