21461731 has 2 divisors, whose sum is σ = 21461732. Its totient is φ = 21461730.

The previous prime is 21461729. The next prime is 21461747. The reversal of 21461731 is 13716412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21461731 - 2¹ = 21461729 is a prime.

It is a super-2 number, since 2×21461731² = 921211795032722, which contains 22 as substring.

Together with 21461729, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21461696 and 21461705.

It is not a weakly prime, because it can be changed into another prime (21461831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10730865 + 10730866.

It is an arithmetic number, because the mean of its divisors is an integer number (10730866).

Almost surely, 2^21461731 is an apocalyptic number.

21461731 is a deficient number, since it is larger than the sum of its proper divisors (1).

21461731 is an equidigital number, since it uses as much as digits as its factorization.

21461731 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1008, while the sum is 25.

The square root of 21461731 is about 4632.6807574017. The cubic root of 21461731 is about 277.8998094871.

The spelling of 21461731 in words is "twenty-one million, four hundred sixty-one thousand, seven hundred thirty-one".