21653707 has 2 divisors, whose sum is σ = 21653708. Its totient is φ = 21653706.

The previous prime is 21653677. The next prime is 21653729. The reversal of 21653707 is 70735612.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21653707 is a prime.

It is not a weakly prime, because it can be changed into another prime (21653747) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10826853 + 10826854.

It is an arithmetic number, because the mean of its divisors is an integer number (10826854).

Almost surely, 2^21653707 is an apocalyptic number.

21653707 is a deficient number, since it is larger than the sum of its proper divisors (1).

21653707 is an equidigital number, since it uses as much as digits as its factorization.

21653707 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8820, while the sum is 31.

The square root of 21653707 is about 4653.3543815188. The cubic root of 21653707 is about 278.7259591699.

The spelling of 21653707 in words is "twenty-one million, six hundred fifty-three thousand, seven hundred seven".