20987547 has 16 divisors (see below), whose sum is σ = 32846592. Its totient is φ = 11668320.

The previous prime is 20987543. The next prime is 20987557. The reversal of 20987547 is 74578902.

It is not a de Polignac number, because 20987547 - 2² = 20987543 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20987499 and 20987508.

It is not an unprimeable number, because it can be changed into a prime (20987543) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12729 + ... + 14282.

It is an arithmetic number, because the mean of its divisors is an integer number (2052912).

Almost surely, 2^20987547 is an apocalyptic number.

20987547 is a deficient number, since it is larger than the sum of its proper divisors (11859045).

20987547 is a wasteful number, since it uses less digits than its factorization.

20987547 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27058.

The product of its (nonzero) digits is 141120, while the sum is 42.

The square root of 20987547 is about 4581.2167597703. The cubic root of 20987547 is about 275.8378721203.

The spelling of 20987547 in words is "twenty million, nine hundred eighty-seven thousand, five hundred forty-seven".