21252651 has 8 divisors (see below), whose sum is σ = 32385024. Its totient is φ = 12144360.

The previous prime is 21252617. The next prime is 21252653. The reversal of 21252651 is 15625212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21252651 - 2⁹ = 21252139 is a prime.

It is a super-3 number, since 3×21252651³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21252653) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 505995 + ... + 506036.

It is an arithmetic number, because the mean of its divisors is an integer number (4048128).

Almost surely, 2^21252651 is an apocalyptic number.

21252651 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21252651 is a deficient number, since it is larger than the sum of its proper divisors (11132373).

21252651 is a wasteful number, since it uses less digits than its factorization.

21252651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1012041.

The product of its digits is 1200, while the sum is 24.

The square root of 21252651 is about 4610.0597610009. The cubic root of 21252651 is about 276.9944305031.

Adding to 21252651 its reverse (15625212), we get a palindrome (36877863).

The spelling of 21252651 in words is "twenty-one million, two hundred fifty-two thousand, six hundred fifty-one".