21471739 has 2 divisors, whose sum is σ = 21471740. Its totient is φ = 21471738.

The previous prime is 21471733. The next prime is 21471743. The reversal of 21471739 is 93717412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21471739 - 2⁵ = 21471707 is a prime.

It is a super-2 number, since 2×21471739² = 922071151368242, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21471733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10735869 + 10735870.

It is an arithmetic number, because the mean of its divisors is an integer number (10735870).

Almost surely, 2^21471739 is an apocalyptic number.

21471739 is a deficient number, since it is larger than the sum of its proper divisors (1).

21471739 is an equidigital number, since it uses as much as digits as its factorization.

21471739 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10584, while the sum is 34.

The square root of 21471739 is about 4633.7607836400. The cubic root of 21471739 is about 277.9429993723.

It can be divided in two parts, 2 and 1471739, that added together give a palindrome (1471741).

The spelling of 21471739 in words is "twenty-one million, four hundred seventy-one thousand, seven hundred thirty-nine".