21980687 has 2 divisors, whose sum is σ = 21980688. Its totient is φ = 21980686.

The previous prime is 21980683. The next prime is 21980719. The reversal of 21980687 is 78608912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21980687 - 2² = 21980683 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21980681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10990343 + 10990344.

It is an arithmetic number, because the mean of its divisors is an integer number (10990344).

Almost surely, 2^21980687 is an apocalyptic number.

21980687 is a deficient number, since it is larger than the sum of its proper divisors (1).

21980687 is an equidigital number, since it uses as much as digits as its factorization.

21980687 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48384, while the sum is 41.

The square root of 21980687 is about 4688.3565350771. The cubic root of 21980687 is about 280.1219154462.

It can be divided in two parts, 21980 and 687, that multiplied together give a triangular number (15100260 = T₅₄₉₅).

The spelling of 21980687 in words is "twenty-one million, nine hundred eighty thousand, six hundred eighty-seven".