21506707 has 2 divisors, whose sum is σ = 21506708. Its totient is φ = 21506706.

The previous prime is 21506669. The next prime is 21506729. The reversal of 21506707 is 70760512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21506707 - 2¹⁹ = 20982419 is a prime.

It is not a weakly prime, because it can be changed into another prime (21500707) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753353 + 10753354.

It is an arithmetic number, because the mean of its divisors is an integer number (10753354).

Almost surely, 2^21506707 is an apocalyptic number.

21506707 is a deficient number, since it is larger than the sum of its proper divisors (1).

21506707 is an equidigital number, since it uses as much as digits as its factorization.

21506707 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2940, while the sum is 28.

The square root of 21506707 is about 4637.5324257626. The cubic root of 21506707 is about 278.0937997572.

The spelling of 21506707 in words is "twenty-one million, five hundred six thousand, seven hundred seven".