21421651 has 6 divisors (see below), whose sum is σ = 22135956. Its totient is φ = 20729700.

The previous prime is 21421627. The next prime is 21421657. The reversal of 21421651 is 15612412.

It is not a de Polignac number, because 21421651 - 2⁵ = 21421619 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21421657) 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, 10185 + ... + 12106.

It is an arithmetic number, because the mean of its divisors is an integer number (3689326).

Almost surely, 2^21421651 is an apocalyptic number.

21421651 is a deficient number, since it is larger than the sum of its proper divisors (714305).

21421651 is an equidigital number, since it uses as much as digits as its factorization.

21421651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22353 (or 22322 counting only the distinct ones).

The product of its digits is 480, while the sum is 22.

The square root of 21421651 is about 4628.3529467836. The cubic root of 21421651 is about 277.7267081166.

The spelling of 21421651 in words is "twenty-one million, four hundred twenty-one thousand, six hundred fifty-one".