21787413 has 16 divisors (see below), whose sum is σ = 29975616. Its totient is φ = 14065920.

The previous prime is 21787411. The next prime is 21787453. The reversal of 21787413 is 31478712.

It is a happy number.

It is not a de Polignac number, because 21787413 - 2¹ = 21787411 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21787411) 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, 36445 + ... + 37037.

It is an arithmetic number, because the mean of its divisors is an integer number (1873476).

Almost surely, 2^21787413 is an apocalyptic number.

It is an amenable number.

21787413 is a deficient number, since it is larger than the sum of its proper divisors (8188203).

21787413 is a wasteful number, since it uses less digits than its factorization.

21787413 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 964.

The product of its digits is 9408, while the sum is 33.

The square root of 21787413 is about 4667.6988977439. The cubic root of 21787413 is about 279.2984691454.

It can be divided in two parts, 2178 and 7413, that added together give a triangular number (9591 = T₁₃₈).

The spelling of 21787413 in words is "twenty-one million, seven hundred eighty-seven thousand, four hundred thirteen".