21100401 has 24 divisors (see below), whose sum is σ = 35647040. Its totient is φ = 11775456.

The previous prime is 21100399. The next prime is 21100403. The reversal of 21100401 is 10400112.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21100399) and next prime (21100403).

It is not a de Polignac number, because 21100401 - 2¹ = 21100399 is a prime.

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

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21100403) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1186 + ... + 6603.

Almost surely, 2^21100401 is an apocalyptic number.

21100401 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21100401 is a deficient number, since it is larger than the sum of its proper divisors (14546639).

21100401 is a wasteful number, since it uses less digits than its factorization.

21100401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7845 (or 7842 counting only the distinct ones).

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

The square root of 21100401 is about 4593.5172798195. The cubic root of 21100401 is about 276.3313993387.

Adding to 21100401 its reverse (10400112), we get a palindrome (31500513).

The spelling of 21100401 in words is "twenty-one million, one hundred thousand, four hundred one".