21401051 has 4 divisors (see below), whose sum is σ = 24458352. Its totient is φ = 18343752.

The previous prime is 21401047. The next prime is 21401053. The reversal of 21401051 is 15010412.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21401051 - 2² = 21401047 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21401053) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1528640 + ... + 1528653.

It is an arithmetic number, because the mean of its divisors is an integer number (6114588).

Almost surely, 2^21401051 is an apocalyptic number.

21401051 is a deficient number, since it is larger than the sum of its proper divisors (3057301).

21401051 is an equidigital number, since it uses as much as digits as its factorization.

21401051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3057300.

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 21401051 is about 4626.1269978244. The cubic root of 21401051 is about 277.6376548331.

Adding to 21401051 its reverse (15010412), we get a palindrome (36411463).

The spelling of 21401051 in words is "twenty-one million, four hundred one thousand, fifty-one".