21507604020787 has 2 divisors, whose sum is σ = 21507604020788. Its totient is φ = 21507604020786.

The previous prime is 21507604020779. The next prime is 21507604020899. The reversal of 21507604020787 is 78702040670512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21507604020787 - 2³ = 21507604020779 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21507604020787.

It is not a weakly prime, because it can be changed into another prime (21507604020737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753802010393 + 10753802010394.

It is an arithmetic number, because the mean of its divisors is an integer number (10753802010394).

Almost surely, 2^{21507604020787} is an apocalyptic number.

21507604020787 is a deficient number, since it is larger than the sum of its proper divisors (1).

21507604020787 is an equidigital number, since it uses as much as digits as its factorization.

21507604020787 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1317120, while the sum is 49.

The spelling of 21507604020787 in words is "twenty-one trillion, five hundred seven billion, six hundred four million, twenty thousand, seven hundred eighty-seven".