20210021001 has 6 divisors (see below), whose sum is σ = 29192252570. Its totient is φ = 13473347328.

The previous prime is 20210020973. The next prime is 20210021021. The reversal of 20210021001 is 10012001202.

It can be written as a sum of positive squares in only one way, i.e., 17065503225 + 3144517776 = 130635^2 + 56076^2 .

It is not a de Polignac number, because 20210021001 - 2¹¹ = 20210018953 is a prime.

It is a super-2 number, since 2×20210021001² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 2245557889 = 20210021001 / (2 + 0 + 2 + 1 + 0 + 0 + 2 + 1 + 0 + 0 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20210021021) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1122778936 + ... + 1122778953.

Almost surely, 2^20210021001 is an apocalyptic number.

It is an amenable number.

20210021001 is a deficient number, since it is larger than the sum of its proper divisors (8982231569).

20210021001 is a wasteful number, since it uses less digits than its factorization.

20210021001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2245557895 (or 2245557892 counting only the distinct ones).

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

Adding to 20210021001 its reverse (10012001202), we get a palindrome (30222022203).

The spelling of 20210021001 in words is "twenty billion, two hundred ten million, twenty-one thousand, one".