21263087 has 6 divisors (see below), whose sum is σ = 21541968. Its totient is φ = 20987772.

The previous prime is 21263083. The next prime is 21263089. The reversal of 21263087 is 78036212.

It is a happy number.

It is not a de Polignac number, because 21263087 - 2² = 21263083 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21263083) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4538 + ... + 7944.

It is an arithmetic number, because the mean of its divisors is an integer number (3590328).

Almost surely, 2^21263087 is an apocalyptic number.

21263087 is a deficient number, since it is larger than the sum of its proper divisors (278881).

21263087 is an frugal number, since it uses more digits than its factorization.

21263087 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3565 (or 3486 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 21263087 is about 4611.1914946139. The cubic root of 21263087 is about 277.0397619593.

Adding to 21263087 its reverse (78036212), we get a palindrome (99299299).

The spelling of 21263087 in words is "twenty-one million, two hundred sixty-three thousand, eighty-seven".