21437887 has 2 divisors, whose sum is σ = 21437888. Its totient is φ = 21437886.

The previous prime is 21437881. The next prime is 21437891. The reversal of 21437887 is 78873412.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21437887 is a prime.

It is a plaindrome in base 11.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21437881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10718943 + 10718944.

It is an arithmetic number, because the mean of its divisors is an integer number (10718944).

Almost surely, 2^21437887 is an apocalyptic number.

21437887 is a deficient number, since it is larger than the sum of its proper divisors (1).

21437887 is an equidigital number, since it uses as much as digits as its factorization.

21437887 is an evil number, because the sum of its binary digits is even.

The product of its digits is 75264, while the sum is 40.

The square root of 21437887 is about 4630.1065862462. The cubic root of 21437887 is about 277.7968557149.

The spelling of 21437887 in words is "twenty-one million, four hundred thirty-seven thousand, eight hundred eighty-seven".