21790051 has 2 divisors, whose sum is σ = 21790052. Its totient is φ = 21790050.

The previous prime is 21790007. The next prime is 21790079. The reversal of 21790051 is 15009712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21790051 - 2¹⁵ = 21757283 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21789998 and 21790025.

It is not a weakly prime, because it can be changed into another prime (21790001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10895025 + 10895026.

It is an arithmetic number, because the mean of its divisors is an integer number (10895026).

Almost surely, 2^21790051 is an apocalyptic number.

21790051 is a deficient number, since it is larger than the sum of its proper divisors (1).

21790051 is an equidigital number, since it uses as much as digits as its factorization.

21790051 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 630, while the sum is 25.

The square root of 21790051 is about 4667.9814695433. The cubic root of 21790051 is about 279.3097410914.

Adding to 21790051 its reverse (15009712), we get a palindrome (36799763).

The spelling of 21790051 in words is "twenty-one million, seven hundred ninety thousand, fifty-one".