21487051 has 2 divisors, whose sum is σ = 21487052. Its totient is φ = 21487050.

The previous prime is 21487009. The next prime is 21487079. The reversal of 21487051 is 15078412.

It is an a-pointer prime, because the next prime (21487079) can be obtained adding 21487051 to its sum of digits (28).

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21487051 - 2⁷ = 21486923 is a prime.

It is not a weakly prime, because it can be changed into another prime (21487001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10743525 + 10743526.

It is an arithmetic number, because the mean of its divisors is an integer number (10743526).

Almost surely, 2^21487051 is an apocalyptic number.

21487051 is a deficient number, since it is larger than the sum of its proper divisors (1).

21487051 is an equidigital number, since it uses as much as digits as its factorization.

21487051 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 21487051 is about 4635.4127108597. The cubic root of 21487051 is about 278.0090528943.

The spelling of 21487051 in words is "twenty-one million, four hundred eighty-seven thousand, fifty-one".