21939277 has 2 divisors, whose sum is σ = 21939278. Its totient is φ = 21939276.

The previous prime is 21939241. The next prime is 21939361. The reversal of 21939277 is 77293912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16491721 + 5447556 = 4061^2 + 2334^2 .

It is a cyclic number.

It is not a de Polignac number, because 21939277 - 2¹⁵ = 21906509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21939977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10969638 + 10969639.

It is an arithmetic number, because the mean of its divisors is an integer number (10969639).

Almost surely, 2^21939277 is an apocalyptic number.

It is an amenable number.

21939277 is a deficient number, since it is larger than the sum of its proper divisors (1).

21939277 is an equidigital number, since it uses as much as digits as its factorization.

21939277 is an evil number, because the sum of its binary digits is even.

The product of its digits is 47628, while the sum is 40.

The square root of 21939277 is about 4683.9381934436. The cubic root of 21939277 is about 279.9458951582.

The spelling of 21939277 in words is "twenty-one million, nine hundred thirty-nine thousand, two hundred seventy-seven".