21148251 has 8 divisors (see below), whose sum is σ = 28885584. Its totient is φ = 13754880.

The previous prime is 21148249. The next prime is 21148271. The reversal of 21148251 is 15284112.

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

It is not a de Polignac number, because 21148251 - 2¹ = 21148249 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21148241) 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, 85846 + ... + 86091.

It is an arithmetic number, because the mean of its divisors is an integer number (3610698).

Almost surely, 2^21148251 is an apocalyptic number.

21148251 is a deficient number, since it is larger than the sum of its proper divisors (7737333).

21148251 is a wasteful number, since it uses less digits than its factorization.

21148251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171981.

The product of its digits is 640, while the sum is 24.

The square root of 21148251 is about 4598.7227574621. The cubic root of 21148251 is about 276.5401232558.

The spelling of 21148251 in words is "twenty-one million, one hundred forty-eight thousand, two hundred fifty-one".