21372151 has 2 divisors, whose sum is σ = 21372152. Its totient is φ = 21372150.

The previous prime is 21372149. The next prime is 21372157. The reversal of 21372151 is 15127312.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21372151 - 2¹ = 21372149 is a prime.

Together with 21372149, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21372157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10686075 + 10686076.

It is an arithmetic number, because the mean of its divisors is an integer number (10686076).

Almost surely, 2^21372151 is an apocalyptic number.

21372151 is a deficient number, since it is larger than the sum of its proper divisors (1).

21372151 is an equidigital number, since it uses as much as digits as its factorization.

21372151 is an evil number, because the sum of its binary digits is even.

The product of its digits is 420, while the sum is 22.

The square root of 21372151 is about 4623.0023794067. The cubic root of 21372151 is about 277.5126244831.

Subtracting from 21372151 its sum of digits (22), we obtain a square (21372129 = 4623²).

Adding to 21372151 its reverse (15127312), we get a palindrome (36499463).

The spelling of 21372151 in words is "twenty-one million, three hundred seventy-two thousand, one hundred fifty-one".