21758051 has 4 divisors (see below), whose sum is σ = 24866352. Its totient is φ = 18649752.

The previous prime is 21758041. The next prime is 21758053. The reversal of 21758051 is 15085712.

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 21758051 - 2¹⁴ = 21741667 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21758053) 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, 1554140 + ... + 1554153.

It is an arithmetic number, because the mean of its divisors is an integer number (6216588).

Almost surely, 2^21758051 is an apocalyptic number.

21758051 is a deficient number, since it is larger than the sum of its proper divisors (3108301).

21758051 is an equidigital number, since it uses as much as digits as its factorization.

21758051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3108300.

The product of its (nonzero) digits is 2800, while the sum is 29.

The square root of 21758051 is about 4664.5526044842. The cubic root of 21758051 is about 279.1729463898.

The spelling of 21758051 in words is "twenty-one million, seven hundred fifty-eight thousand, fifty-one".