21120001 has 16 divisors (see below), whose sum is σ = 26904960. Its totient is φ = 16139520.

The previous prime is 21119999. The next prime is 21120017. The reversal of 21120001 is 10002112.

It is a cyclic number.

It is not a de Polignac number, because 21120001 - 2¹ = 21119999 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (7).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21120041) 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, 2410 + ... + 6931.

It is an arithmetic number, because the mean of its divisors is an integer number (1681560).

Almost surely, 2^21120001 is an apocalyptic number.

It is an amenable number.

21120001 is a deficient number, since it is larger than the sum of its proper divisors (5784959).

21120001 is a wasteful number, since it uses less digits than its factorization.

21120001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9384.

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 21120001 is about 4595.6502260290. The cubic root of 21120001 is about 276.4169335631.

Adding to 21120001 its reverse (10002112), we get a palindrome (31122113).

The spelling of 21120001 in words is "twenty-one million, one hundred twenty thousand, one".