21940951 has 2 divisors, whose sum is σ = 21940952. Its totient is φ = 21940950.

The previous prime is 21940949. The next prime is 21940969. The reversal of 21940951 is 15904912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21940951 - 2¹ = 21940949 is a prime.

Together with 21940949, it forms a pair of twin primes.

It is equal to p_1385770 and since 21940951 and 1385770 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21940981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10970475 + 10970476.

It is an arithmetic number, because the mean of its divisors is an integer number (10970476).

Almost surely, 2^21940951 is an apocalyptic number.

21940951 is a deficient number, since it is larger than the sum of its proper divisors (1).

21940951 is an equidigital number, since it uses as much as digits as its factorization.

21940951 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3240, while the sum is 31.

The square root of 21940951 is about 4684.1168858174. The cubic root of 21940951 is about 279.9530150754.

The spelling of 21940951 in words is "twenty-one million, nine hundred forty thousand, nine hundred fifty-one".