21526649 has 2 divisors, whose sum is σ = 21526650. Its totient is φ = 21526648.

The previous prime is 21526633. The next prime is 21526663. The reversal of 21526649 is 94662512.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11560000 + 9966649 = 3400^2 + 3157^2 .

It is a cyclic number.

It is not a de Polignac number, because 21526649 - 2⁴ = 21526633 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21526619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10763324 + 10763325.

It is an arithmetic number, because the mean of its divisors is an integer number (10763325).

Almost surely, 2^21526649 is an apocalyptic number.

It is an amenable number.

21526649 is a deficient number, since it is larger than the sum of its proper divisors (1).

21526649 is an equidigital number, since it uses as much as digits as its factorization.

21526649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 35.

The square root of 21526649 is about 4639.6819934129. The cubic root of 21526649 is about 278.1797269573.

The spelling of 21526649 in words is "twenty-one million, five hundred twenty-six thousand, six hundred forty-nine".