21629887 has 2 divisors, whose sum is σ = 21629888. Its totient is φ = 21629886.

The previous prime is 21629863. The next prime is 21629893. The reversal of 21629887 is 78892612.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21629887 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21629687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10814943 + 10814944.

It is an arithmetic number, because the mean of its divisors is an integer number (10814944).

Almost surely, 2^21629887 is an apocalyptic number.

21629887 is a deficient number, since it is larger than the sum of its proper divisors (1).

21629887 is an equidigital number, since it uses as much as digits as its factorization.

21629887 is an evil number, because the sum of its binary digits is even.

The product of its digits is 96768, while the sum is 43.

The square root of 21629887 is about 4650.7942332466. The cubic root of 21629887 is about 278.6237181953.

It can be divided in two parts, 216 and 29887, that added together give a palindrome (30103).

The spelling of 21629887 in words is "twenty-one million, six hundred twenty-nine thousand, eight hundred eighty-seven".