21372253 has 8 divisors (see below), whose sum is σ = 24582272. Its totient is φ = 18201456.

The previous prime is 21372233. The next prime is 21372269. The reversal of 21372253 is 35227312.

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

It is not a de Polignac number, because 21372253 - 2¹³ = 21364061 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 (21372233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8625 + ... + 10822.

It is an arithmetic number, because the mean of its divisors is an integer number (3072784).

Almost surely, 2^21372253 is an apocalyptic number.

It is an amenable number.

21372253 is a deficient number, since it is larger than the sum of its proper divisors (3210019).

21372253 is a wasteful number, since it uses less digits than its factorization.

21372253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19611.

The product of its digits is 2520, while the sum is 25.

The square root of 21372253 is about 4623.0134111854. The cubic root of 21372253 is about 277.5130659649.

Adding to 21372253 its reverse (35227312), we get a palindrome (56599565).

It can be divided in two parts, 21372 and 253, that multiplied together give a triangular number (5407116 = T₃₂₈₈).

The spelling of 21372253 in words is "twenty-one million, three hundred seventy-two thousand, two hundred fifty-three".