21493051 has 4 divisors (see below), whose sum is σ = 21857400. Its totient is φ = 21128704.

The previous prime is 21493033. The next prime is 21493057. The reversal of 21493051 is 15039412.

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 21493051 - 2²¹ = 19395899 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21493057) 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, 182086 + ... + 182203.

It is an arithmetic number, because the mean of its divisors is an integer number (5464350).

Almost surely, 2^21493051 is an apocalyptic number.

21493051 is a deficient number, since it is larger than the sum of its proper divisors (364349).

21493051 is an equidigital number, since it uses as much as digits as its factorization.

21493051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 364348.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 21493051 is about 4636.0598572495. The cubic root of 21493051 is about 278.0349273784.

The spelling of 21493051 in words is "twenty-one million, four hundred ninety-three thousand, fifty-one".