21961767 has 4 divisors (see below), whose sum is σ = 29282360. Its totient is φ = 14641176.

The previous prime is 21961741. The next prime is 21961781. The reversal of 21961767 is 76716912.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21961767 - 2¹² = 21957671 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21961727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3660292 + ... + 3660297.

It is an arithmetic number, because the mean of its divisors is an integer number (7320590).

Almost surely, 2^21961767 is an apocalyptic number.

21961767 is a deficient number, since it is larger than the sum of its proper divisors (7320593).

21961767 is an equidigital number, since it uses as much as digits as its factorization.

21961767 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7320592.

The product of its digits is 31752, while the sum is 39.

The square root of 21961767 is about 4686.3383360573. The cubic root of 21961767 is about 280.0415202034.

The spelling of 21961767 in words is "twenty-one million, nine hundred sixty-one thousand, seven hundred sixty-seven".