21275951 has 4 divisors (see below), whose sum is σ = 21962304. Its totient is φ = 20589600.

The previous prime is 21275941. The next prime is 21275981. The reversal of 21275951 is 15957212.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21275951 - 2⁶ = 21275887 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21275941) 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, 343130 + ... + 343191.

It is an arithmetic number, because the mean of its divisors is an integer number (5490576).

Almost surely, 2^21275951 is an apocalyptic number.

21275951 is a deficient number, since it is larger than the sum of its proper divisors (686353).

21275951 is an equidigital number, since it uses as much as digits as its factorization.

21275951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 686352.

The product of its digits is 6300, while the sum is 32.

The square root of 21275951 is about 4612.5861509570. The cubic root of 21275951 is about 277.0956196536.

The spelling of 21275951 in words is "twenty-one million, two hundred seventy-five thousand, nine hundred fifty-one".